My ex-partners parents have a total of 15 GC, 5 of whom are my DC. Three of the GC are constantly given preferential treatment, from weekly sleepovers to holidays with the Grand parents. I used to comment on this to my ex but stopped when I realised what an impossible situation I was putting him in. My DC have asked a few times why they don't get to sleepover etc. but I have so far managed to distract them from a proper answer.
This year, their DD will be taking the DC to his parents house on Christmas Eve and I know they will notice three stockings hanging over the fire with their cousins names on. Just those three. None for the other DGC's, who will all visit and see the stockings for the "chosen ones".
AIBU to think it's a really shitty thing for them to do and to wonder why they don't see how hurtful it is?