If its, say, roots coming in through bad joints, landlord pays.

After its primed, caulk all the joints and corners.

I am a fellow MArch joint degree at UofI (got my MBA too).

Unfortunately, the investors that we've funded are very busy using our funds for their project and we've actually done a few joint venture deals with some of them. 

Developing a solution for an operator is not cut and dried:The state or states you operate in will make a difference;The size and number of loans you are capable of, and willing to, produce will make a difference;The type of loan - real property or chattel will make a difference.When people contact our consultancy for help like this, the very first thing we do is sit down face to face with all principals and ask many, many questions before we make any concrete suggestions, or start jointly planning strategies.

Co-tenants are or can be, held jointly and severally obligated, I'd suggest that approach.At her rent level, she still has discretionary income remaining after rents, you need to ask yourself is it reasonable for her to cover her obligations and have amounts remaining for living expenses?

I personally don't like any growing in my rentals because of the water, heat, humidity are all negatives to a healthy house.

you could also have them take title as joint tenants

If married filing jointly, you may use the full $25,000 allowance if your MAGI is $100k or less, meaning if you have a $25,000 rental loss which you actively participated in, you can use the entire loss to offset your ordinary income.

Could that be done IF they were not investing JOINTLY.... basically each doing individual projects with NO 'mixed funds' so to speak?