My partner has been potty training his 3.5 yo daughter since April 2024, and she is still having accidents (mostly poos) in her pants every couple of days. Obviously there are loads of factors but is this normal? She has had stretches of a few weeks when we thought she had cracked it but then she backslides. My partner has her 50-50 with her mum, and her mum is not communicative about what goes on during her time, or proactive about cracking it. My partner did the original long-weekend of initial potty training himself despite her saying she would help, and she has made slow progress since then but consistently poos her pants.
She is in a mix of nursery and days with her mum, both sides of grandparents and my partner - also not sure about how potty training works on her days with her mum's mum due to lack of communication from that side. So she has a lot of transitions to deal with (also on a 2-2-3 day model split between my partner and his ex). She has nice underwear, steps to reach the toilet, etc. We've had sticker charts and rewards work, we have books, we have done loads of the tricks like bubbles/ glitter in the bathroom. My partner is trying to transition her to have longer blocks of time between him and his ex, now that she is older, hoping it will help her to have less frequent transitions. Nothing seems to be sticking.
My little boy (same age) is also around her a lot and she sees a good example from him - he cracked it in 3 days and has never had an accident, and also naturally night-trained himself a few months ago with no input from me. I know he is probably not the norm and we don't compare her to him.
She's a clever girl and good at communicating on everything except this. When we try and ask her about what she can feel etc. she clams up and just repeats whatever she thinks we want to hear. She is on medicine to help constipation but we're not 100% sure that is the issue. She will go off quietly and poo in her pants no matter how many times we try and communicate about going to the toilet. Sometimes it's small and sometimes a proper explosion, including at nursery. On the couple of occasions my partner has lost his temper it seems to slide off her back. By nature she is cheery, quick to temper and quick to recover and pretty stubborn! She loves pretending to be a baby and will put on a baby voice when she wants something etc. and we've recently tried to gently discourage this in case she is getting something from all the attention around it.
Any tips or perspectives? Most things I read say you have to not put pressure on them, but how are we supposed to get her to care?