Gonna say you are SOL on that one. Given all the options you have to bind tags to properties, pass parameters and reference them in expressions it's not something I think to be possible.
You would never find a tag in an expression like:
tag({plc} + "\TT" + {instrumetnNumber}), which would be looking at PLC1\TT101
Or an indirect binding of {1}\TT{2}
Use drag and drop to help build the structure you intend to use. I applications where people just drag everything in as Ignition would bring them into the system and it can turn messy very quickly.