TOPIC:

I came across two brothers that I wanted to add. I could add one unlinked, add a father or mother with no name, then add the other brother to that family.

But if I could add an unlinked family from the control panel, then at that daily, I could click "add a son" twice. So I think it would be useful to add family to the list of unlinked records in the control panel.

Honestly, this doesn't make sense. Nowhere does webtrees support a family with no individuals. The moment that you delete the last individual from a family, webtrees deletes that family as well.

So the best solution to add an unlinked family is the one you have just outlined very well.

Why not add the father with surname and no first name?
Also add a "Research" task to find more details ;-)

A family needs to have at least one member - and gets deleted automatically when there are no members.

So, you'd need at least one member - which means it isn't unlinked.