Adoption

nightowl explained like that it makes perfect sense.
I knew it was the right thing to tell the child they were "chosen" but I see now the reasoning behind the SS request, and I eat my words

Start now so that he will never know any other . Make up a story about how thay wanted a child but did not have any and how they were so lucky to be able to get this lovely child. I fostered for years and my daughter even when under two understood about birth mummies and chosed mummies.
Adopted children always remember how they loved to hear how they were the chosen one. Leave it too long and someone else will tell them and it is devastating .Even if you are the one telling them it is traumatic , children hate secrets kept from them.

Congratulations Hattiehelga on your fourth grandchild. I have professional experience of adoption, and can perhaps explain that the advice your DD has been given is based on the notion that adopted children should ideally not remember being told they were adopted, but should grow up feeling they had quite simply always known it. That way it never comes as a shock, or a secret, but is simply a part of their life story. It makes no difference to how much they are loved, or makes them any less a part of their family.

Enjoy every moment

I'm delighted for you and your family that this little one has found a home with you all.
I have no experience of adoption but personally I think two is too young to take it all in and that it would be best to wait a few years.

Two is too young , they all need to settle as a family and can a two year old understand

I have an adopted granddaughter who will be five in April and who has been in our family since she was nine months old. She is very settled in a loving, caring home with my eldest son and his wife. They have always taken the view that they will tell her when they feel the time is right for her. I must say that for a child of two I would have thought it a little early no matter what the current thinking is.
As a family we have always avoided the subject in front of the child and my grandson but all the adults in the family know the view of my eldest son and his wife and accept that. Hope that helps a little.