Any property that has reached that financial situation is a liability and has reached it's sale point.I would be looking to sell and reinvest in income producing properties.The exception would be faith investors that rely entirely on appreciation and have the deep pockets to carry a negative income investment property.

There are many investors who's goal is different which is to focus on cash flow but those investors are probably doing well financially.

It all depends on your financial goals and how you want your portfolio looking 5-6 yrs from now. 

#1 or #3 make financial scenes.

If you want to help her out financially, this is not the way to do it.Now to specifically answer your question.

As a general rule (as I have been told by financial advisors), you should not put money into the stock market unless you are planning on leaving f it there for 5 years.If your investment is 3 years off, I would consider investment in a note fund that has a 3 year maturity.

For me (and my personal struggles) I found military schooling to be very financially challenging when it really shouldnt be.

However, you may have a hard time finding a seller who will take second lien because they potentially end up with nothing (not even a property) if your financial situation goes belly up. 

If not, then I'd say it all comes down to your financial situation. 

There are tow reason to get into REI as I see it.1 - Financial.