a sensor just sends out a signal how many units receive it are almost unlimited. You did not say what thermometer sensor, or which HD display you were thinking about. Not all of their temp / humidity sensors work with the Access unit so I cant answer your question any better.
Hello Dantek, A sensor can connect to its display and the Access at the same time. Going off what Ledrak says, the 5in1 HD Display is not compatible with additional 2in1 sensors. The 5in1 HD will only support the 5in1 and an add on lightning detector. The lightning detector is not currently compatible with the Access. Please let us know if you have any other sensors. Thank you.