Purchase Order Variation Primary Contract Document

Hello Community, we are implementing Procurement Contracts in 12.1.3 and I'm keen to know if there is the ability when Managing Contract Documents on a Purchase Order variation to get the Primary Contract Document Flag defaulting as "Yes".

Current default is for the contract document loaded for variation not to be the Primary Contract Document, we would like the opposite to be the default.

I have not found a profile option to do this, so wondered if anyone can be of assistance.

Thanks in advance,

Kirsten