Append Sales Team to Null.

I wish to continue to keep my sales team members assigned to their customer records but upon invoicing I would like to stop NetSuite from prepopulating the Sales team tab of the invoice. I would like the person preparing the invoice (or our current maintenance script) to make that decision. I want this because I do not want my forecast reports attribute a sales rep to maintenance revenue. In a perfect world I would source the sales person / sales team if the  invoice was of a specific order type (think of it as a classification).

Any help would be appreciated. Trying to accomplish this is multiple ways with no success.