Judithjack1, I totally understand how you feel, and it's all completely natural. Having had (have) a very good, close relationship with our DS and DiL, we saw no reason why, when our first GC arrived, that we should be made to feel hurt/left out.
However, it wasn't our DS or DiL that made us feel this way, it was the maternal GM herself. We did get along quite well with her, for years, until GC arrived, but then she suddenly treated us as though our GC was nothing to do with us. At a time that should've been happy for all the family, she deliberately made us feel extremely awkward, and excluded. She has always been quite a bossy/intimidating person, and likes to have things her own way (even her own daughter recognises this). We decided to stand back and let her get on with it, as we didn't want to cause any upset to our DS & DiL by saying anything out of turn.
I hasten to add that our DS & DiL knew that we were always available if they needed anything/help in any way. And we always made ourselves useful when visiting by cooking meals and cleaning, etc. Of course, I understand that most DDs will gravitate towards their own mother when they have a baby, I have been in this situation myself, and I certainly never had any intentions to encroach on that. But, this behaviour from the maternal GM was totally uncalled for and out of order. Our son has since said that he realised what had happened and he wasn't happy about it, and he basically simply tolerates his MiL so as not to cause any upset to our DiL.
I guess, what I'm trying to say is that it's not necessarily the DiL who is making the paternal GPs feel left out of things. Sometimes, there's a driving force behind it all.
At one point, things did come to a head between maternal GM and myself. There had been so much upset caused by her, to both my DH and I, that I couldn't contain myself any longer, I simply had to say something. Not particularly proud of the fact, but something had to give. Thankfully, we managed to iron out our differences, and we now have a mutual respect for one another as grandmothers. We both do what we can to help out with the GCs when needed, and we both get called upon quite often (sometimes, too often!
). Oh, and we both have a great relationship with our GCs. So, just be patient, it will happen!