You could use territories to accomplish this. Your territories do not have to be location based. When you set up the territories you can add a primary sales rep and secondary ones. That might be the easiest.
We have added a second sales person field to the customer master.
In our case we have an inside sales person and outside sales person assigned to a customer.
If you added these UD fields to the customer, you could then build a BPM to pull that data into the order.
Mr. John: Thank you for the suggestion. We had not thought of the “Territory” construct.
That would work to assign multiple sales people. However we would have to come up with some other way of assigning the rates and splits for each sales person per customer.
Exhaust the built in functionality where you can. I am not sure there is any to add a second sales rep. I heard it reported that if you have a task on your quote it will add that assigned to person to the list of sales reps as well. I don’t like the idea of having to add a task to get a second salesperson though.