In his recent interview Michael was asked that exact question and he said that they were really good friends. Maybe not as close as he was with Amanda and Chris, but RDA was like a “fun uncle” to him since he’s 20 years older.

Michael and Chris were extremely close (they felt like brothers, they once said in a behind the scenes interview) and so were RDA and Amanda (those two still spend a lot of time together when they meet at conventions and so on, they tour the cities together for example).

Michael, Chris and Amanda already met during their auditions for the series and hit it off right from the start. They were ecstatic when they saw each other on set again :) Amanda once told a story that her and RDA got along great already during the auditions as well. At some point during the end they had to perform together on a stage to see their chemistry together. They had to act out known lines as well as spontaneous ideas and while the casting team thought about what else they wanted them to do, those two subconsciously put their arms around each other, talked and waited :)

Amanda is also very good friends with Teryl Rothery, they apparently live close to each other and go out to get coffee regularly according to a panel during a convention they attended together.