If you switch the order of the members in the squad XML, the one who gets applied is changed.
This happens because both me and my wife have our own profiles on the same machine. We also have duplicate profiles on another, less powerful machine, which we use when playing together. These have other player IDs, obviously.
Currently I'm using the following workaround:
* On machine 1, player 2 is considered the "extra".
* On machine 2, player 1 is considered the "extra".
* Create another squad.xml (squad2.xml) with only the "extra" members in it.
* Change the "extra" profiles on each machine to point to the squad2.xml file instead.