Rob A couple of things to check.
They are linked by UTM entrance coordinates. I tried to make a KML file and got the error message: georeferenced -- unable to export KML file The fixed points is in the surveys (.th file with distance, compass, cline data) that contain the respective entrances.
Make sure the surveys with fixed points have the coordinate system set, otherwise you are just specifying an arbitrary coordinate system as far as Therion is concerned. ie cs EPSG:2193 # or UTM or whatever you are using. And then each centreline will need to have a date defined, so that Therion can determine the magnetic declination for each survey. ie date 2015.04.18 As an added touch you can specify the coordinate system for outputs in the thconfig file like this ... legend on endlayout cs EPSG:27200 export map -fmt xvi -layout GloryOle -o GloryOle.xvi ... ie you can use a variety of input coordinate systems, and specifically generate outputs in any (relevant) coordinate system all within the same dataset. See the Therion Book page 14 Bruce