(as long as they sign the consent form)I bought a duplex where one side already has a tenant.

These clauses usually covenant that “in any sale, transfer, assumption or assignment of the contract or the property covered by it, the consent of the (lender/owner, etc.) must be first had and obtained.”

Ohio is particularly clear:  You need to have the written consent of the actual owner of the property to advertise.

If you are eligible for a truly self-directed Solo 401k plan then it might be an option for you as well, since it does not require custodian consent. 

With regards to transferring to an LLC - the lender typically doesn't consent to this and could enforce the due on sale provision that is likely in the loan document.

We copy ID, pay stubs, collect app fees and have applicants sign credit check consent.  

I know that in order to assign, I need written consent from them, but they insist that the assignee has to be somebody they know.

We had to put a stop to it.Consider adding a property rule, such as this:AERIALS/ANTENNAE/CABLE/DISH.Tenant agrees to not install or cause to be installed any aerials, antennae, cable, dish or other telecommunication equipment without prior written consent of Landlord.Such installation, if not done properly, could result in structural damage.Landlord or Landlord’s representative must be present at all installations.

I doubt they would consent to that anyway.

The quick version is we had something called a “consent agreement” prepared by an attorney and signed by a tenant & judge.