Should the salesperson's name on the invoice go away EVERY time an invoice is changed (adding items, deducting items)?

First an invoice is a final sale and should not be changed, use an estimate for instances like that

Yes it goes away because there is a chance that the salesman has changed

First of all we are in the roofing business and yes, invoices can and will change (Wood, etc.) and why would the salesperson's name change?  He is the one that sold it.

It's just annoying I have to go through every week and add them back in. :(