[Therion] Add Coordinate data back at last level of Survey Hierarchy?

HI, I was trying to join a file [with Centreline driven by .3d data (.3d)] to another file [with centreline driven by my electronic surveying data (Elec)]. The .3d file seems to come with it's own coordinate system, so we needed to remove(#) the entrance coordinates, from the Elec data. I have joined these two surveys in a .th file and successfully got an output. There are two entrances to the system. So my question is, can I add back coordinate data for one (or more) Entrance(s) at the last level of the survey hierarchy? or will the mismatch between .3d and Elec prevent me from doing this? Regards, Alastair Gott. AlastairGott@hotmail.com, M: 07931779380,