I have these shackle props that go on the ankles and wrists of a character. 4 smart props all positioned correctly and work great. The only problem was I'd have to add each one seperately and I'd have 4 props in my prop folder. What I wanted was a prop that had all four shackles set up as smart props in one file so I click on one file and voila. So I thought, well why not just concatinate the 4 prop files together. Well with a little fudging IT WORKS!. Basically I added each prop after the version section but before the document section and made sure each prop had a unique name. Then I added the control lines to the document section at the bottom for each prop to attach them to their respective parts and matched up the names. Works like a charm. I can now couple earings together into one file (each earing being a smart prop), couple arm and leg props into one file and so forth. Its very handy. This is different than the subset option which I don't believe will remember smart props.