I am using THR316D as temperature / humidity monitoring device only. At the start I was using only one sensor THS01 as factory design is.
Soon I had to measure in another room and I simply use potential free contact on THR to switch between data lines of both sensors. I fixed 3,3 V power to suply both sensors all the time. I found that configuration is 100 % reliable and works very well.
After some time I get cheap further Si7021 sensors and wanted to expand measurements to all important rooms in the house. Fortunately I have more than enough UTP wiring around the house, to do that. Now I am using modified (relay contacts freed from 230 voltage) 4CHR3 (interlock mode enabled), to switch dataline between 4 channels plus aditional 4x toggle relay controlled from THR potential free contact. This configuration gave me efective 8 independent remotely controled monitoring channels. It is simple possible to add one more for total of 9, when all is off via additional NC relay and four diodes.
At the moment I am using 7 sensors, 4 of them are about 50 meters away and everything works perfect and 100 % reliable. The only potential problem I am worried about is suplying sensors with 3,3 V voltage.
I measured current and each sensor needs about 6-7 mA. It means that now I am a little under 50 mA total. I have no idea about THR16D 3,3 V power suply capabilitiy, and be very glad if someone could provide me with this data.
I also thought about option to switch not only data line of sensors but power line too. I found it is a bad idea, because each sensor needs some time (few minutes) to stabilize output data after power suply is connected
Just for information. Now i have final number of total 10 Si7021 sensors constantly powered by one THR316 D and all of them works perfect.
I added one more relay (controled same as existing 4x togle) to toggle between two sensors connected to additional NC relay, to raise total number to 10.
One of sensors is connected via more of 70 m UTP cable and still reliable, others are 50 m or less.
So it looks that 3,3 V power source of THR 316D is capable to supply 70 mA on 24/7 basis.
You can use DS18x20 sensors and connect them in parallel. Only challenge is that for as far as i know the standard THR316/320D firmware is not supporting multiple temp sensors on one device, nor does the current cube API.
I have flashed mine to Tasmota and have connected 2 sensors so far.
On my iHost, I had to use MQTT and NodeRed to create 2 virtual device that shows up in my cube. It now shows as 2 separate virtual temperature sensors each with their own graph.