Well...
There is a reason we have not posted anything on this particular question, or its cousin - what happens when you want to change career specialisation, do you just move or do you en-enlist?
That's because, so long as you are consistent in your own games, it really doesn't matter - it works either way. You are not going to break the game or unbalance a character by making the wrong choice. Because of that, we have been somewhat reluctant to make a firm ruling. On the issues in, say, Mercenary and High Guard, it is easy to come down on one side or the other but this seemed... a bit greyer, if you know what I mean.
So, no definititive answer as yet, and whichever way you are doing it is right (as long as you keep doing it that way!).
Sorry!