Keisha:
You are SOOOO not being over-protective!! I would be FURIOUS!!
While the legal age of leaving a child home alone is 12 - I would NOT leave several girls (or boys) home alone for that period of time. That is just plain irresponsible.
TOO many things could've gone wrong. Simple stuff too - what if they were playing make up/dress up and one had an allergic reaction to the makeup? What if one had been laughing so hard and stuck the mascara brush in her eye? REALLY?! I know it sounds far fetched - but things like this have happened. 12 year olds can panic and panic kills. Or worse yet - party time!! Mom's away - come on over!!! THAT would've been bad - VERY BAD!!
What if the mother had gotten in a car accident? There are just way to many things that could've gone wrong - they didn't, thank God, but they could've very fast and very easy!!
Stick your ground!! If the mother questions you - simply explain that even though they are 12, too many things could've gone wrong - you EXPECT an adult in the house with the girls.!!