Is There a Custom to Combining Hyphenated Last Names?

Factual Questions
1

The title isn’t completely descriptive, but I hope it is sufficient to not mislead anyone.

Laugh if you will, but here’s my question, asked in complete ignorance:

Let’s say John and Mary Smith-Brown’s child marries Jim and Marsha Attenborough-Riley’s child. They are American or British (no Spanish-type naming customs in other words.)

Assume the children are also into the combining-last-names thing.

What would they choose as their married names?

I’m pretty sure it would NOT be Smith-Brown-Attenborough-Riley. But, I don’t know what they would pick, or how or why.

I know, talk about trivial. But I really wonder about this. Is there an accepted procedure here?

2

I don’t think there’s a single rule. But the logical thing - to me - is for children to take the first last name of their mother, and the second last name of their father, thus each name representing an unbroken line of either female or male ancestors.

3

Laugh-In had a running series of jokes made by taking famous people’s names and marrying them in combinations so that when added all together and hyphenated, their names made whole punning phrases.

4

From memory: “If opera singer Wanda Walensky married Howard Hughes, then divorced him and married Henry Kissinger, she’d be Wanda Hughes Kissinger now”.