Vic, why do you do this? First off, 'modifying' speakers for hanging is a good way to go out of business. If the speakers don't have flypoints, DON'T FLY THEM! Those Yamahas are NOT designed to be flown. Read this, especially page 2:http://soundsolutionscanada.com/technical/unsafe/
Second, every installer knows that you make money selling equipment, not doing plain labor. If the cheap POS Behringer mixer fails under warranty, they'll call you, and want you to do the call for free. Sounds like they have no money. I'd thank them for the inquiry, I'd point out why they should return everything, and then buy a system from you. If not, walk from it, and let someone else inherit the headache.
Behringer is the worst commercial crap out there. Lower than low. I won't sell it, let alone install it. FYI.