The age-old "selection – and custom groups" UX probem

Say you have a list of let's say 30 "friends".

Now there's a concept, "select some of them" to perform an action. No problem. You bring up a list with checks down the side, the user checks what they want, perhaps five of them.

As the universe evolves, the developers let you "create groups".

So of the 30, I can make say four groups

  • friends
  • online friends
  • buddies
  • siblings

each one would be able to be edited, deleted and renamized. and of course you can "add a new" custom group.

I have two questions,

(1) I am trying to think of an app or www that has an example of this. There is one on the tip of my fingers - there's a really well-known example of this but I am damned if I can think of it ! Truly appreciate any examples

(2) In the opinion of Us, (surely the last word in UX opinion), how do you go about this?

So step 1, you click "send" (or whatever) and the

  • normal list (of 30) appears; you can tediously select some. this is "ad hoc" selection

Then, you're going to have a list (four in the example above) of "custom groups" (which you have previously made)

  • instead of adhoc selection, you can select one of your saved groups

Should those be on the same screen as the ad-hoc screen (perhaps at the top?), or should you have to navigate to even select one of those from another screen, or perhaps a popup, or?

Then the issue of, you have to be able to

  • edit/delete/rename - and indeed "add a whole new one" - of the custom groups

Again, I would love to see some major examples of this - I am blanking on thinking of some. And secondly - how to?

(A final point - is there a good name for this concept? the adhoc one we see all the time is just "multiple selection", perhaps this is best called "saved groups" or "custom presets" or something.)