Training entertainers

[Fairy Lily]

I'm lucky enough to be overwelmed with work at the moment (touch wood)
and have decided to take on some people and train them up to assist me
at parties and also to be hired out through my company to try and cover
the bookings I can't do.
Does anyone have any experience with this as I'm slightly concerned
they may just wait till I've trained them then go solo leaving me in
the lurch and with more fairy entertainer competition?!
I know from reading Silly Billy's book (my working bible!) he has done
this but there is no mention of any leaving him for a solo career and
using his routines.
Any tips and advice would be very much appreciated!