Kris: I have a debt & equity firm that arranges financing for commercial and multifamily real estate.  

Is there a particular agency that is better than another for this type of arrangement whether it be fee structure or training?  

Researching markets, fostering relationships with brokers, finding and vetting deals, obtaining experience, raising capital, arranging bank funding, vetting management companies...the list goes on...is hard work; so, the deal structure is set up so that the sponsor gets compensated for that work with a 70/30 split rather than proportional.  

@Nolan Martineau, I also suggest you make sure that the arrangement you have with your family member is in writing.

How do you arrange payments (partial upfront, with balance at completion)?

If you call the store manager of any big box store and tell him your business is rehabbing apartments and you would like to start a purchase arrangement with his store, you can expect 10-15% discounts off of the shelf price. 

Not only do you need a new contractor but may need someone to step into their PM shoes.Many owners have made these type casual arrangements work but there are inherent risks.A PM on the other hand is in the business of providing a service and also, I believe, has fiduciary duty to you.

You will be sacrificing getting on with your real estate experience and holdings, but would be doing a good thing for aging parents and will have a good asset paid down and ready when you are both ready for other living arrangements.  

Mario, while it can be difficult to find someone interested in the kind of arrangement you describe, you also may not be legally entitled to any rent for a residential unit that does not have its own certificate of occupancy.  

That contract arrangement would be void.