How do I get my 15% of construction costs from the customers preferred subcontractors if he’s withholding receipts?

I’m a project manager who’s company GCed a multi million dollar residential project for a cousin. Originally my brother started the project with his own company. He didn’t submit a bid to receive a deposit, and spent 45k of his own money before submitting an invoice (which I did for him). Both parties wanted me apart of the multi-million dollar project so I formed an LLC with my brother. The customer wanted to do time and material so I told them both I need 2500 a week, 22% for our company payroll and 15% from any subcontractors he preferred working under our license. We end up with a verbal agreement( big regret) for him to pay my company 15% of the cost as he sales each building. The sum was projected sales was around six million dollars. My business partner (brother) and myself would be paid 1500 a week a piece as an advance. 5-6 months into the project the PoS customer decided he’s not selling the property. I reminded him that since he’s not selling and he wants to turn his project into a Time and Materials job what the cost will be and that I needed receipts from all subs working under our license. I asked one of the foremen from one of the subcontractors, that I developed a relationship with, to forward me one of their approved bids only to be told, a few days later, that the customer didn’t want me to have that information. I confronted my relative with this information only to be hit with another lie saying he didn’t say that and he would forward me what I needed. I left a short time later after we couldn’t reach an agreement after he refused to forward receipts. I have all the information related to what I’m owed in personal wages and 22% from our company but since he never turned over a receipt/ approved bid how do I go about putting a dollar amount of what I’m owed?