I am really confused. These are her kids - she has everyright to the certificates - but why have you got the children's certificates when they live with their Mum???

I don't know about changing their names - I don't thinkit's an easy process to change a childs name legally. However, she can call them whatever she wants - so basically they can use her name and that does not need to go through BDM... If of course she wants to alter their name officially she would need to go through BDM.

I would just think she wants to keep their originals. You need birth certificates for lots of things. Not sure why she didn't just apply for new ones.