On Thu, 26 Sep 2013 23:35:42 -0400, Ed Pawlowski wrote:

You can be pretty sure that you don't own it. From the scenario you
describe, probably No 1 owns it since they bought #2.

I have come to this realization that you are probably correct.
I don't own the tank.
They probably own it.

Your opinion does not matter.
I agree.

unless you have a bill of sale
I do not.

you did not buy it.
I now agree.

If a propane company does not own the tank they are not
allowed to fill it.

Actually, they fill their tanks and your tanks but they
won't fill a tanks that they know to be owned by a third
party.