I hate to tell you this OP but it doesnt just stop at your kids.
DP has a sister who is the golden child she is about 8 years older than DP.
Sister has kids - golden grand kids. Our DS was largely ignored, treated the same money wise with gifts but time wise, he hardly saw them and they couldnt be bothered.
Dp and I had a surprise baby when we were 40, a girl, no other babies around, Sisters kids were now adults. Just before DD was born, Golden Grandchild announced she was pregnant and gave birth the next day (long story, dont ask) we were all dragged to the hospital to see the baby.
DD was born 4 weeks later, none of the fuckers came to the hospital to see her. DP had to beg his mum to come and see DS when he was born all those years ago, i wouldnt let him beg again so they didnt see DD till she was about 2 weeks old.
And now DD is ignored in favour of Golden Great Grandchild. Infact both Golden Grandkids have had more kids so poor DD is pushed further down the pecking order.
My DS became a father, his DD is 1, my grand daughter is beautiful so another Great Grandaughter for DP's parents. No, they couldnt give a shit about her either. At her first birthday party they were "on their way" and never turned up. Didnt answer mobiles.
I do not have a good relationship with them due to all this and when i saw them a couple of days after the party incident i totally blanked them, they were bloody luck as i was so close to giving them what fucking for.
With a bit of luck they will be dead soon (mid 70's now) so my grand daughter will never know how unloved by them fuckers she is.