I think I know what we are going to do, but I'd like some other opinions.
Imagine you have a BIL/SIL whom you're not close to and the bond is not one of blood.
Year 1: everyone gets on well, presents exchanged at Christmas.
Year 2: you haven't fallen out, but SIL has made it clear she dislikes everyone in the family and feels sorry for her DH not having a family he can count on. Everyone rather confused but since BIL himself doesn't say anything, assume it is 'just her'.
People buy presents for them as normal at Christmas; they give Oxfam gifts (without warning).
Year 3: some of the family respect their wish not to have 'things' at Christmas and buy for their children. Others buy them presents, as normal. They buy for the children only.
Year 4: gifts are bought for their children. They do not buy any for the children, or anyone else.
Year 5: ?????