The solution that was initially proposed was that friend/business partner would have his 25% equity split bought out of the funds that the 3 equity/capital partners are bringing to close and then he would take 25% of the backend profits.

But the solution cannot always be to throw more money at a problem.Again, the government is focusing on the easy-button solution when it comes to higher housing related costs.

Any solution for minor sound proofing fixes that may be able to work?

The tax treatment of replacing HVAC systems depends on various factors, including the type of property (residential or commercial), the cost of the systems, and whether they qualify for immediate expensing or need to be depreciated over time.For residential properties, the cost of replacing HVAC systems is typically considered a capital improvement rather than a repair.

The financial solution can be self management or a full time manager. 

This method minimized financial risk and maximized efficiency, highlighting Partner Driven's ability to leverage creative financing solutions for successful real estate ve How did you add value to the deal?

The solution going forward is don’t agree to terms with wholesalers that have study periods unless the DD period is reasonable and/or you can still market until the $ goes hard. 

And you have the longer-term solution of REI.

Document EVERYTHING... every conversation, every contact, every document from the remediation company etc etc etc.Then I would send him a certified letter that states all necessary precautions, accommodations and solutions were done.

At that point, it's worth researching and finding a solution that better meets your needs.