Australia 3 Phase CT set up clarification


I’m currently working with a small business which previous to me starting had an IoTaWatt system set up to record data of the various equipment we run. Recently we’ve wanted to change some of the connections, which is moving 2 of our CT’s from single phase devices over to 2 separate 3 phase devices. Initially I didn’t change the phase of these devices, but after confirming which phase was correct these were changed.

However, these didn’t seem correct as to what we thought we should be getting. I then spent the following afternoon changing the phases (A,B,C,A-B,B-C,C-A) (while keeping the CT on one wire) which of course all produced different data ranges. The next day I’ve tried focusing on one of the 3 phase devices and have set up a CT on each lead and set them to the appropriate phase. These all produce the same data, although offset from each other by a small amount. My main cause for confusion is that we have another 3 phase unit set up (before I started), but only one one phase being measured with no scaled output.

Can I please clarify the following;

-For 3 phase systems, do I need to have a separate CT set up for each phase? Am I able to set up some sort of output to measure a combine of all three phases while only monitoring one phase?
-For the currently set up 3 phase system being monitored by one output, should I do the same as above or keep monitoring as we have been previously? (one phase monitored with no adjusted output)