We use DDM files across 3 machines.
Identify the file (PF or LF) on box 1. Then on box 2 use CRTDDMF and fill in the file name & library from box 1. For Remote Location, we use the IP address (so type is *IP).
Note that the file names do not need to match across boxes. It is useful to have meaningful names, though (e.g. a DDM over our ITEMS file on the U.S. box might be named ITEMSUS on other boxes).
You can’t query nor SQL the DDM file but you can write single records to it via a program (I never tried CPYF but seems like that should not work).