sub contracting refer challens in migo

Dear all

I have a scenario in sub contracting process when we create sub contracting challans for for material to send to sub contacting vendor

Ex : main material 20 qty

sub contracting material 20 qty

we create 4 sub contacting challans with 5 qty each

when we do the MI GO we are referring 2 challans only but system is not stopping the GR

Please any one suggest me to solve the problem

Regards

krishna