Configuring Wacom one to overlap on a third screen and map it appropriately

I am a teacher and I have some students in the room and others via web, using  3 screens my laptop + a Wacom one tablet + a video projector screen.  I need to  (using an HP zbook 15u G3 wich can use 3 screens) 1) sync the video projector screen  with  [ a part of ] my 'Wacom one' screen. 2) Map the stylus only to the Wacom one's screen ( so I can see what I am writing by just looking at my tablet) So far I was able to do - (1) but not (2) with plasma - and (2) but not (1) with gnome.  With plasma even with only 2 screens I was not able to get a correct mapping using kde-config-tablet app (the result was always that  moving the stylus across tablet will mean moving the pointer from the left of one screen to the right of the other). I suspected it is bugged but maybe I am just stupid enough not to make it work... With Gnome the mapping was correct (limited to the tablet) but I could not have anything else than an extended desktop, where the video projector's screen and the wacom's  screen are next to each other and not sync (nor overlapping) . Pretty Please If someone know any solutions. I am very willing to try (even with command line tool [xrandr?]) I desperately need this to work!