> Replying to a tweet will also prefill the @handle of anyone mentioned in the tweet. Replying to a retweet will additionally prefill the @handle of the person who retweeted it. The original author’s @handle always appears first. In some cases, it’s polite to remove some of these; you only need the original author’s @handle to make a reply. (It’s not uncommon to accumulate multiple mentions, then end up in an extended conversation with only one other person, while constantly notifying several third parties. Or you may want to remove the @handle of a locked account that retweeted a public account, to protect their privacy.)
I wish they would fix this already. Twitter users are constantly embarrassing themselves by @mentioning the retweeter in their reply.