If not rented at fair market rent, this property will just count as your residence, not a rental for tax purposes.Structuring the property under an LLC or land trust could trigger a due-on-sale clause, so check with the lender before proceeding.To minimize risk, consult a CPA for tax strategy, weigh financing costs, and draft a legal rental agreement.

Their insurance has asked me to return the month's payment for the remaining days of their rental (Unfortunately, I did not have a cancellation agreement).I am unsure how to handle this situation, especially since I couldn't fill the majority of the rental dates and had to offer discounts for the days I did manage to book.

Your operating agreement would have to specify exactly what you can do with those monies.  

Sounds like this is a private money lender or a hard money lender.If you are getting funds from another source and relying on that to close, you should not put in the purchase agreement that you are buying with cash.

For contracts, consult a real estate attorney and use standard assignment agreements to stay protected.

How to Structure the Deal to Protect Your $20KIf you’re willing to cover the $20K arrears, here’s how to protect yourself:Option 1: Secure Your Funds with a Lien or Escrow AgreementUse an escrow account: Deposit the $20K into escrow with clear terms—if the assumption is denied, the funds return to you.Record a promissory note & lien: If the deal falls through, this would give you a legal claim against the property to recover your funds.Option 2: Sub-To + Wrap While You AssumeSubject-to deal: Take over the existing loan payments before assumption approval, securing control.Escrowed deed transfer: The seller signs the deed into escrow only to be recorded after assumption approval, ensuring they can’t back out.Lease option fallback: If the assumption is denied, consider a lease option agreement until another solution is found.Option 3: Negotiate a Seller Financing HybridAsk the seller to carry a small second note for the $60K equity gap at favorable terms.Use your $20K as a down payment, structured as a secured loan against the property.3.

Apparently they take preferred interest in your company or have you sign a UCC cash flow agreement.

houston is probably similar pricing to Columbus Ohio but way worse zoning laws. we take 20% on top as a GC and a guaranteed fee agreement. our contracted new construction projects recently:Single family new build spec home: 1513 square feet with 3 beds 2.5 baths 1 car attached $275000 approx $182 a square foot if calculated using heated square feet which means our cost is $145 a square foot. 3 unit / triplex new construction: 2008 square feet 2 bedrooms 1 bath per unit or total 6 bedrooms 3 bathrooms with 3 off street parking spaces. contracted build cost $395,000. no garage on this and better economies of scale with shared roof, slab, etc. $192 a square foot hard cost with our cost running approximately $157 a square foot. 

Another right of an LLC Member is to get copies of all Operating Agreements.

I'm not a fan of novations where you don't get the purchase agreement notarized and filed at the courthouse.