Board Thread:Questions and Answers/@comment-16461120-20160405223613/@comment-26100657-20160406024854

Okay, sure, they fought alongside the Avengers. But we clearly saw some kind of "induction ceremony" at the end, introducing the new Avengers lineup. I think that was when Scarlet Witch, Vision, Falcon, and War Machine officially became Avengers, nevermind that they had been allies before then (Scarlet Witch, Vision, and War Machine all assisted in the battle against Ultron, while Falcon fought alongside Cap and Black Widow in the past). Quicksilver was also an ally in Sokovia, but didn't live long enough to make it into the new lineup.