Elizabeth Olsen and Aaron Taylor-Johnson are the Scarlet Witch and Quicksilver in Avengers 2

[Umbran]

That is a completely separate issue from what teams they where on and for how long. As such you have switched arguments.

Not at all. What teams they were on, and for how long, speaks to which license(s) they fall under.

Anyway, 'X-Men: Days Of Future Past': Evan Peters Is Quicksilver... But What About 'Avengers 2'? so they may have a licencing snarl in the works.

That story is from back in May - if there was a real snarl, there'd have been more hoopla about it. My understanding is that both the Avengers and X-men licenses may use Quicksilver and Scarlet Witch. There's just some restriction about what can be said about them.

In an X-movie, they can't mention Quicksilver being in the Avengers, or the plotline of the Avengers movies. In Days of Futures past, this is likely not an issue, as they'll probably using a *young* Quicksilver, before he ever joined the Avengers.

In an Avengers movie, they can't mention Quicksilver being the son of Magneto, or go into the "mutants vs the world" plotline.