I am not able to reproduce this internally. If I have 4 clients separated into two squads, both with a commander leader, only the commander can initiate a merge. I also confirmed this to be the case on live thanks to some players testing it for me. There could be an edge case that we missed, if anyone can figure out a way to reproduce this please PM me (Don't post it here) how you did it so I can work on a fix. As of now, without reproducing it I can't fix it. Parties merging into parties is getting looked at separately.