trying to get child to change a parents variables

i'm making a tower defense game and am having problems with projectiles, the projectile gets to the enemies and destroys itself fine but i need them to deal damage equal to the tower they are created from. can parenting be used like that? this is from the towers create event

damageact=25;
experience=0;

and this is from enemies collision with the projectile

experience+=damageact

the projectile is the towers child, nothing happens.