Due to age gap my dniece is only 5 years younger than me.
Dsis met her current dp when dniece was 9, and her dp had two dc's, aged 9 and 11. They live with their mother but see their df regularly, and they've always spent Xmas day with their dm.
At Xmas myself and family so mum, dad, other siblings would always give dniece a 'proper' present. Then send a token gift to dsis stepchildren such as a selection box. All of their names always went on cards.
This has gone on for years and all of the children are now adults in their late 20's and one has moved out etc. we still send a proper gift to dniece and a token to stepchildren wine, beer or chocs. None of the children including dniece send anything back or write a card which is fine.
But it now turns out that dsis is really angry that the family haven't treated the stepchildren the same as her dd for all these years and has fallen out with us over it.