Yes, I believe our above friends have answered this question.
When a new baby arrives, the entire household changes.
Routines get upset, and feathers can be ruffled, with the older siblings.
Backsliding does occur at this time with the potty training.
Almost would be better to just ignore it for a while, until
the schedule with the future newborn, and big sister
gets into a good routine.
I found a good blog from Valorie that might be helpful:
http://baby.families.com/blog/tales-...otty-the-rules
(((Hugs)))