She moved into the house while the sick sister stayed with other family.

It's likely that the maintenance responsibility could be specifically defined in the lease but you should get an attorney guide the board through the process.

He will want to stay involved with the property long after his financial investment is paid back, to get the most bang for his buck which I'm fine with, but I want to create clear expectations for his future return. 

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This is obviously location and property specific, but we're working with partial numbers so far...let's assume you'd want to stay in the cabin on vacation:)  If we find a place for $300k with 25% down at 5% interest, conduct $50k of value-add rehab...renting it 12 weeks/year breaks the project even on a cash-flow basis incorporating all costs.  

Eventually causing me to stay overnight, duhh..So, at what point does residency become an issue if I have a loan (FHA or VA) that requires occupancy?

I've also heard you can close the property to a Land trust with Trustee of your choice and then after closing have them resign and you be the successor trustee but they stay on public record.

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