Take the advice you receive here on BP with a grain of salt.

My friend has dismissed their threats of taking legal action in the past on things like no salt on sidewalks while it is still snowing....but what if?

As others have mentioned agents advice should be taken with a grain of salt. 

You simply take her calls with a grain of salt and as time passes she will learn you do not feel the same urgency with her issues as she does and she will stop calling except for major problems.

That's my $0.02, w/o any experience with  student  rentals, so take it with a grain of salt :)

I'm not sure about Maryland law so please take this with a grain of salt: it seems to me the squatter was invited by the tenants, who may have breached their leases by having someone stay overlong, but if he's there when the house is sold, you will have to evict him because he had an uncontested right to be there. 

If they tell you to rub salt or ask for help you have two options.1)  File an eviction notice 2) File an eviction notice and tell them if they are out before it is completed you will withdraw it. 

I just moved from living with my parents in Arlington, Texas to living with a boatload of roommates in Salt Lake City, Utah.. and you wouldn't believe the amount of connections you can make just by surrounding yourself with people everyday, especially new people (Go to REIA's).

Take it with a grain of salt.

They will soon be ex-tenants so if they can not work with me I politely suggest they can rub salt.