I'm coming to the realisation that you can't change a units side. Yes, you can change its group from one side to another.
I just tried the following
Set a trigger activation anybody.
activation=[psuedoEastUnit] join RealEastGroup;[psuedoWestPlayer] join RealWestGroup
I had a west soldier as player (psuedoWestPlayer)Rank Private grouped to a civilian sergeant
I had a East soldier as player (psuedoEastUnit)Rank Private grouped to a different civilian sergeant
I had a west soldier Rank Major with RealWestGroup=group this in his init
I had a East soldier Rank Major with RealEastGroup=group this in his init
I then walked into the trigger.
Results? psuedoEastUnit hared off to reform with the RealEastGroup while My new officer told me to rejoin formation.
I went a step further, since the above had obviously changed the groups correctly. This time in the trigger I added
[psuedoWestPlayer] join grpNull;[psuedoEastUnit] join grpNull
and reran it.
Results? psuedoEastUnit stays where he is, and I don't get told to rejoin. I then walk infront of psuedoEastUnit. He stands, patiently waiting for something to happen. I shoot ground. He lays down, then gets back up and resumes waiting for a bus or something.
Analysis - Changing groups does not seem to make the blindest bit of bloody difference.