Yes, talk to your free lawyers, as Realtors, we are not allowed to give any "lawyerly" advice.
You're not purchasing this as an investment or rental property, which I believe is what the language from Chase states.
They are protecting your loan (owner occupant with less restriction) against an investment purchase, which is riskier with more hurdles to jump through on approval.
Essentially, if you purchase and they're still there, you do indeed in language have landlord/tenant rights, but this isn't something that needs to be recorded - ie, you could grant them a few days free of charge in order to move out, etc.
I'd closely review the paperwork with your attorney and Chase and call your Chase advisor to let them know this is not an investment purchase, etc.
In a short sale, most lenders will require both the seller and buyer sign an "arms-length affidavit" as part of the short sale. I'm surprised that you did not sign one. That affidavit will state that the buyer cannot sell the property back to the seller and the seller cannot remain in the property as a tenant. Anyone experienced with short sales knows that this is standard with the lenders. Both agents should be aware of this.
Also, the short sale approval letter would have stated the terms of the short sale. Again, the seller and both agents should have been privy to these conditions when they received the approval.
Kathy Persha, Realtor
Keller Williams Realty