My 34 year old son and my 10 year old grandson live with me (I'm 57); we rent a house. A few houses over my older son & his girlfriend & her 4 kids were living; but now they aren't together anymore But the kids still call me gram.. My son that lives with me bought his son a 4 wheeler. The other kids had permission from their mother that they could ride the 4 wheeler. The 13 year old fell off backwards while my grandson was driving & hurt her back--- but she said she was ok. She never said anything about hurting her head at all. Now almost a year later she is having headaches & seisures. We don't know yet what is causing them; But if they find out it could be from the fall off of the 4 wheeler, could my son or myself be held liable? My son paid for it & had it registered in his name. Thank you for any help.