What do you mean, use the indoor temp/hygro/barometer for the outdoor readings?
You could put it outside to test for a bit, but it can not be used to report back to VWS as an outdoor temp/humidity. Its also not weatherproof.
You are probably better to either replace the thgr968 or get an additional sensor and do the channel 1 flip...
Andrew
To get mine closer, I put out 4 different digital humidity sensors, averaged them, then took that average and adjusted the calibration in VWS for the Sensor to match that (+10). I still have a channel 1 humidity sensor outside reading, that seems more accurate. So I compare the two once in awhile.
Funny thing with the thgr968 sensor......in regards to humidity, it reads lower than sensor channel 1 when temps are low (30-50) and higher then sensor channel 1 when temps are higher(60-80). (50-60) seems to be the spot when they are both are close. All of this of course still having the calibration applied. I figure if I am within 10% of all the other PWS in my area, I am doing good then.