Marty & @Sam Guarnieri just so you know, land trusts in PA do not offer you any protection, here's an article from a PA Lawyer that i have posted on the site before, with their written permission: http://dornish.net/a-matter-of-trust

Since the adverse possessor is no longer occupying the land under claim of title, but under permission from the record title holder, the adverse possessor cannot obtain title to the property through adverse possession.

I am going to try to get over to the building code department next week to see if it is something permissible in the neighborhood.

Do not no play with or pet a service animal unless its owner has previously given you permission.• Required to wear jackets or vest identifying them as such.• Required to have an identification card or other documentation.• Required to be registered or certified.Handlers may be asked to remove the service animal only when:• The service animal is out of control and the handler does not or cannot take effective action to control it.• The service animal is not housebroken.• In all circumstances, staff must offer the person with disability the opportunity to obtain goods or services without the animal present.Service Animals in Arizona HousingThe federal Fair Housing Act prohibits discrimination in rental housing accommodations against those who use service dogs or animals.

Do you yourself have cash, do you have a buyer already that wants the property,  do you have a title/closing agent lined up, do you have the recent payoff from the bank, has the buyer given you permission to talk with the bank, etc, etc.

And @Wayne Brooks is right, unless you have permission from the seller, the bank won't even tell you that property exists. 

To cover for the earnest money though, we try to keep some cash in the escrow account of our closing attorney to make sure we're covered.As far as your buyer's earnest money funds, those funds are technically separate and as far as I know (and I could be wrong) you're not really supposed to touch them, especially not without their permission.

Maybe in some cases if you have express written permission from the C buyer to do so, but probably not at all if they're using financing (lender won't likely allow it). 

Establish a monetary fine via your rental agreement as a deterrent to tenants allowing others to move-in without your permission.

I’m an advocate it’s better to beg for forgiveness than to ask for permission with the city.