Children's surnames

[3kids1dad]

Hey everyone. Possibly a touchy subject but Google is being of very little use. I'm very undecided on whether to change my kids surnames, and posts I have found here on the subject seem dated.
I have 3 kids, 2 are my daughter's with hyphenated surnames and I'm on BC. 3rd is my ex's son, I'm not on BC and not his dad, but will soon have a court order placing him with me (I'm uncertain to the exact wording but it will give me the PR). His surname is his mother's only, no dad on record and to my knowledge no one knows who he is.
I get a LOT of dodgy looks, invasive questions etc in a day to day life, demanding to know where their mum is, why have we got different names, even to the point where the social worker had to vouch for me so I could enrol them at school/nursery when we moved. I feel like I constantly have to justify our lives, simply on the basis of a name. I'd love to change all 3 to just mine, but A) would that prevent the snide looks/comments/hassle? B) would it be wrong morally to change them just to make things easier? C) would it be like taking their mum away from their point of view?
They are 8 7 and 2, the eldest doesn't like the idea. Their mother was horrific towards them, and there were court proceedings in progress to have them removed from her before she died last year, but end of day, they are kids and she was their mum..can anyone offer advice or any other guys have similar name issues?

It's pretty common for children these days not to share a surname with both parents, both of my grandsons have their fathers' names, and one has siblings with a different name again. It does cause confusion but usually cleared up easily, though I can see having to explain every time would get wearing.
You would need the consent of everyone with PR (or a court order) to officially change their names, but this sounds do-able. But should you? Your eldest is unhappy at the idea, can you explore that further with her? The seven year old needs consulted too, I think.
If, as a family, you decide you want the change, it doesn't have to mean losing all links with their mothers. You could keep photos around in drawers, talk openly (and age-appropriately of course) about their mums when they ask. How.much do they remember of their abuse?

I have no experience of this but I think I would suggest retaining the hyphenated surname (possibly switching so that your surname is first) and then give your boy the same surname as his sisters. This would solve the issue of you being questioned and would help them all to feel they are treated the same as a sibling set.

I say this because I would be concerned that when they are older the children might feel as though you have removed their choice to identify as their mother's children if you take the decision to change their surname.

If your two eldest (daughters) surnames are Mumsname-Yournane, could you leave them alone and change your youngest's name to be his Mumsname-Yourname. So all three would have their mums name and your name, linking them together and to you whilst keeping their link to their different mothers?

So as a family unit you might be

Mr Jones
Miss Campbell-Jones (9)
Miss Campbell-Jones (7)
Mr Smith-Jones (2)

I was going to suggest the same as happy.

Thank you, I felt pretty certain on pushing the hyphenated idea, you have helped clarify it :)
In response to @HirplesWithHaggis, the girls both remember a LOT, especially the eldest who had the brunt of it, the younger was spoiled and 'special, always favoured and could do no wrong. Despite that, it seems to be the eldest to it hurt the most, still screams and throws massive temper tantrums if something breaks, or she loses something, and doesnt share her mums stuff..its all hers without consideration for her siblings. DS doesn't remember her at all, he sometimes pipes up 'my mummy dead' when playing, especially if the girls friends play mummy and daddy type games with dolls, but when we look at photos he can't seem to ID her, recognise her or anything like that. Understandable given he just turned 2 when she passed