If you provide any compensation they must be treated as employees with regard to taxes, workers comp, etc. You must also comply with any state and local laws.
Be sure to base your pay on their effectiveness too. By that I mean that they must be able to relate to these age groups in order to coach and teach them.
The young ex-college grad head coach model is exploding around here, but I have noticed that there are only a few who can relate to the younger age groups. The majority of the ex-college grad head coach attempts around here either 1) try to run a young team like an extreme drill Sargent in an 18 Gold or college team setting or 2) they want to be a friend to all the players and act like just one of the girls. Neither disposition works well.
Common sense would dictate that as a percentage just as many as non-parent coaches. Unless you are suggesting that a coaches familial relationship to a player is somehow correlated to coaching acumen. If so, you truly are Out In Left Field.
I really like my fresh out of college coaches. I am very lucky to have them, and pay them a reasonable wage for their time. I pay an hourly rate for practices, and a flat fee for tournament days. At that age, you should have backups, if practical. They will be looking to do other things, like find a boyfriend, go to graduate school, parties, etc.