I wonder if the expectations were set properly at the start of the season? My rec parents' meeting always includes what I expect from the girls and the parents, and I keep it simple:
Girls: 100% effort 100% of the time
Consequences for less than 100%: less playing time, probably not at favorite position
Parents: cheer all the girls on both teams
Consequences for umpiring, coaching, being abusive/negative: banishment to the outfield, possible ejection from the park
I've yet to have a real problem with a parent (that could be due to having good parents, I'm not taking sole credit).
As rec commish, I would recommend getting with your division manager (and possibly your commish) to discuss the best way to approach the family.
Girls: 100% effort 100% of the time
Consequences for less than 100%: less playing time, probably not at favorite position
Parents: cheer all the girls on both teams
Consequences for umpiring, coaching, being abusive/negative: banishment to the outfield, possible ejection from the park
I've yet to have a real problem with a parent (that could be due to having good parents, I'm not taking sole credit).
As rec commish, I would recommend getting with your division manager (and possibly your commish) to discuss the best way to approach the family.