mr_brightside said:
I've got an easy solution. Take someone that isn't 14.
Hmmm, a very interesting proposition that definately reminds me of the feotus theory of dating.
But more practically you have a few options available.
from the sounds of it her mother is unaware that you are already dating. So it seems like her mum is the kind of person that can give you change when you hand her a 5 cent coin for her not to notice. By this logic you can probably pass off some total fabrication as truth and get your girl away for the formal evening. Something like "Mum, I'm going outside to water the grass. I'll be back before 12" should work a treat
or you can drug her mother up real good. not only will you be able to tell the mother but you can be present while it happens and get the mother to sign a document allowing your gf to go to the formal. better yet you can do this on the formal night and avoid most problems.
you could even try playing the laxatives game. give the mother some laxatives, in biscuits, cake or a method of your choice and turn the mother into a melted chocolate factory. she will be making but gravy you can be at the formal
you see you have many options, but get creative. heck, she could probably walk out the door and get away