And, yes, you can, technically, sell something you don't own.

So, I'm in a situation where I own 3 rentals and I'm looking into mortgaging them to buy some more.My issue is that I'm a bit behind on taxes, I was living overseas for a while and while technically I was supposed to file taxes during the time I was overseas I didn't.

I don't want to bank on appreciation so I am not considering it but I guess technically I should mention that it's a growing city.

JUST KIDDING the depreciation topic for reason has technical books that are 500 pages thick.

I feel that since I'm not dictating the hours he works, where he has to be etc. under the laws of the IRS, he's not technically my employee.

If the LLC is truly disregarded then you could sell as yourself and buy as the LLC and technically you are not changing the taxpayer.   

My question is this still technically abandoned property, or is it just junk they left behind?

I technically have a rental but it doesn't cash flow.

@Neddie Smith I was in a similar situation with a partner of mine (technically, my partner's pension fund) and we discussed this with a very experienced and competent attorney several times. 

Keep in mind even tho they haven’t paid and Loney hasn’t changed hands YOU haven’t given them a late notice or notice to quit so technically since they most likely haven’t been informed in legal fashion, they might have some ground to stand on.