How to set MoM to account for loss of production units?

Where/how would I express a MOM where I expect loss of the production item during processing.

Demand for 5
Job has 3 ops, 1 unit is scrapped at Op 20, 1 unit is scrapped at Op 30
net production is 3

Is there a parameter on either the Part or the MoM that accounts for the loss and ups the job launch by 2?

I've been looking at "scrap", should I be looking at "yield"?