LOL, I fully second the cut the apron strings
I do remember having my sister who is a writer by profession edit some of my college work. However, she never suggested changes to content, just spelling and grammer.
Now, for my almost 9 year old, I do review his writing assignments for neatness (ie, can I read what he wrote?) and spelling and grammer. However, I tell him I saw at least x number of mistakes and make him try to find them. If he can't find the last couple I try to talk him through what he is missing so he still finds them himself. For content he is on his own. If I feel he hasn't quite hit the mark, I will make a copy of it and after he has turned in his work, we will go over it with some suggestions on things he can think about for the next assignment.
I also make a point of letting him read some of my writing to find my errors so he knows that this is just a part of the writing process. Since I am lousy at spelling, he can usually tell me I have x errors to find as well :P.
I'd take the vacation over editing papers anyday
