The lawsuits hit a weak point in the industry, made realtors look ill prepared.

Ask questions and drill down on a few big ones and you will find some weak points if the ship is not run tight. 

Quote from @Kevin Zheng: Hire an attorney immediately and get them out.The tenant can tell your parents are at a loss of how to proceed, so the tenant is taking advantage of that weakness.

I agree that one apartment building seem too weak to require 750 hours' work.

There are so many investment property owners who are only to see weak rental demand...

They are moving a million miles an hour and its hard for them to determine your strengths and weaknesses and how that fits into their needs. 

So I see my offer might be a bit weak.

They have weak contracts and leases if they have any at all.

the answer i'm giving is based on the assumption that you do not want to / can not float the negative cashflow any longer. and note: even if appreciation / debt paydown / tax benefits strongly outweighed the negative cashflow, most investors wouldn't want to / couldn't float that. so that said, i say SELL. you have just over a million dollars in equity (minus transactional costs when you sell), and you could do a 1031 exchange into a ~4 million dollar CASHFLOWING property. i invest long distance into value-add multifamily on the west side of chicago. gearing up for my next deal right now. in that price range you could easily get a value-add multifamily with potential to cashflow 15k/mo+++ (up to 40k/mo) once it reaches its full potential. it sounds like you're in markets that are probably strong for appreciation and weak for cashflow (with the long term rental strategy). if cashflow is your goal, 1031 into value-add multifamily in a higher-cashflow area. don't let having to pay commissions during the sale stop you. you're already losing so much annually; you have to stop the bleeding at some point. also note that right now, with the way these two properties are losing money, that might negatively affect your borrowing power when you go to buy the family home. feel free to dm me if i can help in any way!

I also know my weaknesses: lack of experience in MF, zero experience with underwriting and raising private capital.