Is it normal for a step mother to stop doing pretty much everything they used to help out with for the step child once their own DC is born?
I.e. used to help take to school but now DC is in before school/after school club or parents have to ask other people to help the days they can't.
Used to take them to do things at the weekends, now never does.
Used to be happy to help out if parents were stuck for childcare the odd time but now is often too busy.
Just generally seemed to make more of an effort beforehand.
YANBU - it shouldn't change.
YABU - it's normal.