teenagers or kids, that is the question...

So, the biggest fight I've had with my mom (so far) about the wedding is that my fh and I don't want to invite kids. Here is the post I just left on weddingbee:

So, after incessant fighting with my mother I have given in to one of her demands-- technically we compromised, but now I have another problem. My fh and I did not want to invite kids to the wedding and our definition of a child is anyone under the age of 18. The compromise is that we will now allow teenagers at the wedding, which is apparently defined as anyone 13 or older.
So, here is the problem... How do I word that on an invitation??? What if one family has a 15 yr old, a 13 yr old, and a 10 yr old?? How do I now exclude one, but not the others? Not inviting kids was easy, address the envelope to the invited adults and put "adult reception immediately following ceremony" at the bottom of the invite. Now I have no idea what to do???

I need to order my invitations by the end of this month. Apparently, I have already hurt some family members feelings because my mother told people that we were not inviting kids. I don't know why she did that -- up until this point we'd only been TALKING about it, no decisions had been made. This is all very frustrating. Ugh.