Troops return in wrong general when using mercenaries

On finishing Young Woodcutter I have an MMA and Nusala each recovering with one normal, barracks-trained recruit thanks to the First Aid skill. I also have Anslem recovering with 15 mercenary recruits.

On finishing the adventure the mercenaries run away as expected, however Anslem returns with 2 recruits and Nusala and the MMA have lost theirs.

It's not a massive problem as the expected troops have returned home, but they're not in the general I would expect them to be. I have noticed this twice now.

mercenary troops dont stay in the general you put them in - they are just a counters. If you load a general with normal Recruits and send him to attack and then ( before first general finishes fight ) load another general with mercenary recruits, then it will be the mercenary recruits you loose.
excample - if both generals are loaded with 200 - and first general loose 50 - then second general will ( in theory ) have 150 mercenary and 50 regular recruits ( untill you loose recruits next time )

Suppose it makes sense that the normal troops would have to float around as well then. Just wasn't expecting it on the returned generals.