So there is a #clearrec command - I see it now, it's in the "Name, Era & General" section of the reorganized modding manual, not in the "Unit Lists" section where I was looking for it. Thanks for pointing it out!
This is going to be a big help when it comes to certain nations like the Elves (based on Tir'na n'Og) and the Dwarves (mid Agartha). The units I want to add will duplicate the functions of a lot of the units already there...
By the way, I posted (or thought I did) a thread on unit graphics for this mod, but I don't see it now and searching for it turns up empty. Is it so much of a fax pas to have more than one thread per project that the moderators deleted it, or did I slip and not post it?