Firstly I have to apologise for having a approach this from a viewpoint of almost total ignorance. My brother married a woman who had a son. As far as I know the son has no contact with his father. That said my brother has not adopted this child, nor did his wedding include any promise to look after the child (which I understand he could have chosen to do).
My parents feel very clearly that this child is not their grandchild, which has probably strengthened due to the fact that he would almost always not appear on family get-togethers (with the reason being that he could not cope with a 40 minute car journey), instead choosing to stay with his maternal grandmother.
Since my brother got married, we, and my parents, have always included this sds in present-giving etc. My brother now has a dd. We typically exchange ideas for Christmas presents as we don't see each other that frequently and there can be a fair amount of duplication. This year my SIL has asked my parents to get a set of DVDs costing £70 for the sds. This seems a bit odd given that she had our wishlist where no item was over £20. She is also insisting that my parents give her dd (16mo)some dvds too as she wants the children to be treated the same.
This has wound my parents up somewhat to say the least. They feel that it is insensitive to expect so much more to be spent on a step-grandchild than on their grandchildren and they definitely don't feel that they could afford to spend that amount on all of their grandchildren. They also feel that they shouldn't have to take the place of the sds's grandparents (they know the father, though clearly they don't rate him terribly highly since he is no longer in contact etc).
So I was just wondering how does it "normally" work? Or is it simply the case that there is no normal? Are my parents being too old-fashioned in their views? I suspect that this would be a total non-issue for our family had it not been for the degree of expectation on behalf of SIL.