Advice needed please!

Hey everyone, first time poster here, VERY new to the forum, please bear with me.

A little background: I have four children by three mothers. The mother of the eldest is FANTASTIC, no problem with her at all.

The mother of my second is not so much, but now that said child is an adult, I don’t have to communicate with her anymore, which makes life a little more bearable.

The mother of the youngest two has gone out of her way to remove me from their life. She has met someone else (no problem with that at all, good luck to them, I hope, genuinely, that they’re happy), got engaged, and moved nearly two hours away, taking the children with her. She has requested I change my shift pattern at work to make her life easier; unfortunately for her there are no vacancies for me to change to HER preferred shift pattern. Even if there were, she has booked the kids on activities and into clubs that would greatly impact any time I might get to spend with them. From her doing, I haven’t seen them since October half term of 2023, due to exceptionally unreasonable access demands, which she herself does not adhere to. I have evidence of this, amongst other narcissistic, controlling, bullying and abusive behaviour.

And now we come to the point of this post, apologies for the lengthy intro.

I have had a ‘request’ from the mother of my children to change their surnames by deed poll to hers, in a suspected attempt to further remove me from the kids’ lives, citing that the eldest of our two children has ‘requested her name be changed’ from mine to hers, something I can’t possibly fathom she would request, and their mother also wants to change our son’s surname.

My question is, does she have the right? She has asked my permission, but do I have to grant it? Am I within my rights to decline permission for this?

Thanks in advance everyone, and apologies again for the long post.

Look forward to reading your responses, and any advice will be GREATLY appreciated!

Chris