They should make them act like mercenary bands, not assign them to any courts. These are lowborns, unless adopted by a noble they have no business as regular court members.
They could add a mercenary "court" for each independent realm, and then whenever new retinue leadership is required, it would assign one from the national pool and whenever more is needed they could be added here. Their average skills should also be way lower.
Anyways, this way you could invite them to your court if you liked them (or wanted to give a title out), and when they are all placed in the same location it would be easier to have an event delete them when there are too many.