I found a nice little 2 bed 1.5 bath house renting for $615 asking is $31k looking to make an offer of around $25k.

After his death, it was decided to sell the property.   

The reason for noting the extra tenants is that their children are now grown, but 3 of them are still living in this 2 bed/1 bath, 1050 sq ft home, with the garage illegally converted to an extra bedroom (allowed by my grandpa originally).So, can we ask them to sign this new Rental Agreement and is there any way to request a security deposit at this point in their Tenancy?

Time to re-evaluate plan B (sell), plan C (1031) or plan D (hold until death)!

Not by any means.  24 STRs with 84 beds. 

Is anyone using bed bug spray on their mattresses after a guest checks out?

If you buy a park with $150 rents in a $400 market, you will displace some marginal residents as rents increase.Finally, you will lose residents periodically because of death or some other major life event.What's important is that you be in a position to re-fill these homes or lots as they go vacant.

My only property, is a 3 bed/1.5 bath single family home (SFH), under my LLC.

So sad.."Detectives spoke with doctors from [MedStar] Washington Hospital Center who advised that [the victim] was most likely not going to survive this incident," officers wrote in court documents.
https://wjla.com/...

I purchased it furnished, but I swapped out some stuff, added beds, and did a remodel to add a bedroom.