When creating an opportunity, you have fields for Other contacts, Sales Team, and Competitors all done as sub-grids. I have a "+" sign next to sales team and competitors where I can add one to the opportunity on the fly. For some reason I do not have one next to Contacts.
I have been playing with the properties of the sub-grid, and have occasionally gotten the "+" to show, but when I fixed parts of the view that weren't working for me, the "+" would go away.
What makes that "+" sign show up? Telling our sales monkeys that they have to leave the opportunity and search through their contacts is a PITA.