I know you can post from Mastodon to Lemmy by mentioning the community in your post, but I'm not sure about cross-posting. There wasn't a way to quote post in Mastodon last time I used it, but if that has changed, it may be possible.
@LolaCat@[email protected] Yeah, seems not. I tried mentioning a community in a reply to the original post, but it didn't post there. Only the top level post counts (but keeping the mention is needed for replies to become comments)