MIGO problem for subcontracting PO

dear Expert:

I have a subcontracting PO, the finished goods quantity is 100 PCs and the raw material is also 100 PCs.  when I receipt 105 PCs finished goods on MIGO, the raw material will be updated to 105 automatically, I can understand the automatic update is a standard behavior and it is right.

but my problem that I want to fix the automatic update for the raw material, in other words, I only want to comsume 100 PCs raw material when receipt 105 PCS finished goods or more. how to do this?

thanks and Best regards

Colin Hong