Last names

Up to them !

I have always thought the sensible thing is for the couple each to keep their own name, as my son and DIL have done (they are married) and I wish I had done. Then it has to be decided what surname the children take. I feel the daughters should have the mother’s name and the sons the father’s, but my son and DIL have taken the conventional route and both boy and girl are known by my son’s surname. They have my DIL’s surname as one of their middle names.

I really minded giving up my name, but in 1968 I didn’t have the courage to keep it.

Legally the child takes the fathers name

And in the example above it is more common to be mr and Mrs yx , ie the fathers name is the main name
My girls kept their names , it would have been hilarious if one had done the add on as both names started with Mc

My sons children are double barrelled but will be free to choose to use either one or remain double barrelled as they get older.

My DD's use their own names professionally they are married. The children are registered in their father's name.
I didn't mind giving mine up but I do get asked about my married name as where we are names are very regional . My FIL was the only one in the telephone book at one time.

I’ve always wondered about this too OP!
What will children with two surnames do if they grow up and marry?
What will their children be called?😄 It could get complicated.

In Iceland, daughters take mother's surname and sons the father's. The family are then the AB family. When the children marry, they keep their surname. The adult children repeat this, creating new family names AX, AY, and BZ.

As a teacher I used to hate the double barrelled surnames simply because they took up so much space on the register, peg and drawer labels and name cards. That of course was in the days when everything was hand-written, by the teacher.

I miss my double-barrelled maiden name to be honest.
I continued to use it professionally after marriage and at university for my degrees.

I was pleased when my daughter and husband joined their names in this way and know two families who do the Swedish/Icelandic thing Chocolatelovinggran describes. It doesn't create any problems as far as I can see.

Lots of Welsh names have been hyphenated in the past by the way. It's not a new thing.

Chocolatelovinggran

In Iceland, daughters take mother's surname and sons the father's. The family are then the AB family. When the children marry, they keep their surname. The adult children repeat this, creating new family names AX, AY, and BZ.

That sounds a very sensible system.