When I was saying to mention where poo goes ect it is more just a conversation and just a reminder even though they know kwim? It just helps cement it in thier brains

I hope the mum doesn't undo all your hard work.. you could be sneaky though and say to your Sdd.. I hope you like being a big girl.. Don't wear a nappy when you go home.. or something like that and hopefully when her mum puts a nappy on her she will say no she is a big girl...