In theory after you have made timely payments on their loan that should be considered, but in practice I have yet to find a loan a officer that can package it so their underwriters will except it. 

There are alternatives such as bank statement averages of 12 months, a P&L statement and exceptions to qualify based one year of income. 

My question now is would a lender lend with this exception.

The exception would be if this was already permitted for STR - short term rentals VRBO then it might be worth it based on location.If you just want to buy a home and have a unit to help cover the mortgage I would still insist on lower price point or NO HOA to help get the total mortgage down so that the other unit covers 50% of the overall payment.  

These would also not take too much time except for my partner and I both still working full time jobs in addition to managing real estate so we are open to various ideas that might improve our efficiency.

So yes separation would trigger automatic sell.The exception for this is perhaps midwest.

So, keeping your personal financial statement updated is vital.

Sometimes you will have “frequent flyers” who like to bring up every little thing and seem to have more issues… but they are more the exception.   

Trying to figure out if I would need to permit the property as a mobile home park, or if it would simply be some variation of a Condo except the HOA also includes lot rent payable to the owner and not an HOA. 

BUT, we do see some notable exceptions with condos that perform very well.