My sister is mum to 2 year old twin girls (2yrs 4 months) and is having a really hard time. She has managed to get them to the stage where they will both wee and poo on the potty if they are running around naked but as soon as she puts anything on the bottom half, even just knickers they wee or poo in them. she stays calm with them, tells them where they must go on the potty, that knickers arent nappies etc..
Any ideas?