What to do, if anything?

So feel for you as it sounds like you and your DS have a rocky road ahead with this immature girl, whatever the outcome. Your son needs to know the truth ASAP and not have to live with doubt and uncertainty, plus the child will be entitled to know his true parentage too.

What an unfair moral dilemma.
My concern is....if the child has been fathered by another then that persons medical history is applicable to the child. This could have major consequences as the child grows up.

There is an old saying, 'It's a wise man father that knows his own son.' Of course, the possiblity of DNA put an end to that!
I agree with the majority saying leave well alone. It sounds as if your son is a loving father to this child and that is what is important to them both.
Almost any man can help to produce a child but the important father in a child's life is the one called Daddy.

We were in the same position 20 years ago. My son was only going with a girl 3 months when she announced she was pregnant. She wasn't exactly what I had hoped for my son, he was at college she didn't work, to cut a long story short he stayed with her till gs was 6 months old. We had gs for a week when he was 4 days old and every weekend thereafter. When gs was 9 months old she said she was pregnant again son admitted he had been with her once when collecting gs. Upshot was another gs who looks nothing like my children or any of our other gc. My son went back with her for another year but although admitting he doesn't think he is his, we are the only family he has known he is now 20 and thats the way it will stay.

Yes the others are right- it would have be your son who did the test or you could ruin your relationship with him,do you have other reasons for doubt,i.e. does the child not look like your son or his mum either?what do the mums parents say to all this?or are they not around? IF your son is worried enough he would surely do the test himself eventually?all you can do is ask him or ask if he wants you to pay for test if and when he wants it done.then wait and see..with this girls behaviour it will come to a head at some point anyway probably,as people can only take so much of this kind of behaviour before enough is enough,however much theyre besotted.

Heartbreaking all round but somewhere in the middle of all the stories are little ones who need love and care regardless of their DNA. I can only begin to imagine how hard these situations are for Grans but surely a vulnerable child who has entered into your family circle, however complex the circumstances, needs grown ups to be in their court.

If your son adores the baby and has looked after the little soul from birth, then he IS the father. Being a parent is a far deeper matter than a random sexual act. The baby is innocent and deserves all the love you can give him.
If medical issues occur later in life it may be necessary to dig further, but until that bridge needs to be crossed just keep on enjoying your darling grandson.

Had similar with SIL and an ex before DD married. Ex denied baby was his so a DNA test was done, everyone now knows where they stand (child is his). That is the main benefit of the test - it will also mean that if any incorrect information is given to the child in the future it can be clarified. Re the money - kind of you to help out but are you inadvertently funding her drinking? I feel I am out of date with the care of young children and drinking habits.
If child is not biologically his he can still bring it up should he choose to be involved.

If they "need baby food& nappies" then go to shop& buy them just that dont give out any more cash- how can they afford holiday but not essentials for baby?(maybe she could stop paying for drinking sprees to buy baby things?)I dont mean to sound harsh/mean but it seems like this girls seeing her baby as a cash cow to keep you giving for life.(maybe if your son brings up 'doubts' again you can tell him straight that you wont continue to be generous without real proof that you're the babys real grandparents?)£3k is a LOT of money- and you shouldnt be footing the bill for any mistakes your son makes(the girl&jumping into everything quickly)if hes got any worry about the child he needs to sort it out before he&child become even more attatched to each other as it will cause more upset years down line if hes not childs biological dad.yes anyone can love& bring up someone elses child- but as mentioned in one of the other posts in point of view from a grown up child from that situation can you imagine how devastated youd feel years down line to discover your 'dad' wasnt your dad at all?youd maybe feel cheated and lied to?its not just your sons or the babys mums feelings to consider.But in meantime keep a tight rein on your money and tell them you're paying for your own holiday as you deserve one too.

Do not interfere, it's between your son and his partner.

The baby needs a family. Don't reject him or think of him as not the your DGS. Hi life's chances my depend on your concern and loyalty. Enjoy the contact and stand by him whatever the outcome.

Elrel wow that was really unkind that must of hurt him dreadfully.
Plumblady if it was me I would sit him down and talk to him about it better a dna now than latter! He can get it done without her knowing the letter can go to your house then it's up to him what he's does with the information! at least he will have peace of mind..... and you.

Sorry later not latter

Please speak to your son do not go behind his back, one of my closest friends had the same situation with their son, they helped him care for his daughter when he had her, nearly six years down the line the mother for various reasons had social services involved in her life (she had other children) and the up shot was he wasn't the father of the little girl, the children were placed into care, and due to him not being the biological father he was refused custody. The loss of that little girl caused untold heartbreak for the entire family after 6yrs of believing her to be daughter, grandchild and much loved niece...

I would be concerned about the mother of a six month old going on drinking binges
A work colleague married a guy when she was pregnant by another man. Everyone knew the situation and he and his parents have been far the better family to the child than his blood relatives, even though they are now divorced

Raise your concerns with your son. It is for him to decide what's the best to do. Do not go behind his back - you risk a major fall out by doing so and, additionally, it's disrespectful.

I can understand that you are worried, but you will just have to bide your time and see what happens, as we all have to do at some point in our lives.

I hope everything works out, especially for the child who is the innocent.

We have suspicions about our first grandson too but, when his parents parted company and she moved over 200 miles away with Dad paying a large sum out of his salary plus trips to see him, when we suggested a DNA test, he refused. He felt that the boys was his son regardless of biology and the alternative was to leave the child fatherless. Whilst we were somewhat perplexed by his decision, we were very proud of his morals. Now our grandson is much older, you can definitely see the family likeness and now a half-sibling has arrived, there is much about her that reminds us of our grandson's early years. At 6 months old it is completely impossible to tell parentage by looks! Enjoy building the relationship with your GS and be there to support your son as he navigates his way around the problems of his relationship. I suspect that one day it will come to a head and he will want his mind putting at rest if she keeps putting doubt in his head when she is drunk!

As someone else said family resemblance is not always clear! My middle child did not look like either her father or I (though the eldest and youngest did??‍♀️)
However years later, after my mother died, I came across old photos of a great aunt,from her young days, and there was our middle daughter looking straight back at me ?

This is no easy thing that you're dealing with, but whatever you decide to do, it's not a good idea to go behind your son's back.

Down the road, my biggest concern would be that GF becomes an unfit mother, your son wants custody, she gets the DNA test, real father lays claim and your son loses GS altogether. If by then, the child is old enough to realize what's going on, the worse it will be for everyone.

So, it's better to know the truth now, not later. Talk to your son about a paternity test....it's a good idea (for peace of mind, if nothing else) but the matter is a very delicate one.

I can't tell you how to go about this, except to approach your son when he's alone and in the right frame of mind. Choose your words very carefully and remember that timing is everything.

Would it matter that much if he wasn’t your GS you have obviously made a bond with him anyway. I think it would be wrong to do DNA test it would probably make things a lot worse.
I would certainly be concerned about the mum if she is drinking, and saying comments to your son just be a support to him

Your son, assuming he is on the birth ceritifcate, is the child’s legal father.

He has the legal right to organise a DNA test for the baby. You don’t, and over and above that, it is likely that any attempt on your part to do so will find you completely cut off from that branch of your family.

It is your son’s choice whether or not to have the test done, until the child is old enough to request a test themselves.

Please support him in whatever he decides. However, stop financially supporting them. Even if you did not have the test issue, they need to be able to manage and prioritise their own finances to take care of baby. it is not helpful to enable them to make poor financial choices. Particularly if there are concerns over substance abuse in the home.

Is there not a legal proviso, something like it should only be done if it is in the best interest of the child?

Please, Plumlady, do nothing at all, unless or until your son asks for your advice and help.

In our young days many girls married not the man they thought was the father of their coming child, but the man who was prepared to take the responsibility of helping to bring up the child. By and large the system worked well.

Then DNA testing came along and hey presto, everyone has to know precisely whose child is whose, which illnesses they might possibly develop later in life and frankly, IMO this just causes as many problems as it solves.

In your case, I would not be worrying about whether this child you all love is your son's biological child. If your son had been unable to father a child and he and the boy's mother had adopted or used a sperm donor would that make any difference to your feelings for the child? Surely not!

What I WOULD be worrying about is the drinking sprees this young woman goes on and the fact that she obviously is a "mean drunk" saying (doing?) precisely what she knows will hurt and in the long term do damage.

However, until your son asks your advice about his partner's misuse of alcohol you need to keep your mouth firmly closed on that subject. Although in my candid opinion it is a much more serious problem than who actually fathered the little boy.

Sorry, if I am just adding to your worries and saying something you decidedly didn't ask for advice on, but I have seen all too often the damage a parent's drinking does to children.

I think it is best left alone - if your DS is happy to continue being the Dad. How devastated would your DGS be is he found out his Dad wasn't his genetic father! Children do not always resemble their parents! There are a lot of permutations of genes to be had from previous ancestors.

So this couple have known one another about 15 months and she goes off drinking and getting drunk, this is a terribly difficult situation for you, how old are they? Like others I think you have to keep out of it until your son comes to you, if appropriate you could then suggest a DNA test but what do you think he would do if he found he wasn't the father. What she is telling him, when drunk,is that she had been sleeping around, this is devastating in such a new relationship. I hope you are able to have a conversation with him. With regard to the money I think you should buy the items, nappies etc, for them if you want to and say unfortunately you can't help further.