WEBENCH® Tools/TPS40304: How do I change FET selection to use alternate TI FET combination that is not provided in the predefined list?

Part Number:TPS40304

Tool/software: WEBENCH® Design Tools

I am trying to implement a 3.3V/0.8V design for IMax 8A and 10A.  I have FETs from and existing design that I would like to leverage and simulate.  For example I would like to simulate with single instance of CSD16340Q3 for M1 and M2 however WEBENCH  only allows options for 2 CSD16340Q3 for the low side (M2) and then M1 is fixed to some other combination of single or dual fets.  Please advise.