Sounds like you don't have very much room BEHIND your ears....nonetheless you can STILL be amazed by ATMOS sounds whirling around above your head. And ATMOS 7.1.2 is severely limited anyway....you have to CHOISE whether your want the Height signals to be in the FRONT, OVERHEAD or REAR location anyway....which is why they offer 7.1.4 (and 5.1.4) for a LOT more $$$'s.
Be sure to refer to my fol. three posts....esp. note that the Speakers located in the REAR of the Room are labeled #4
/5 in DD5.1, connected to L/R "SURROUND" AVR Terminals, but become Speakers #7
/8 in DD7.1, connected to L/R "REAR" AVR Terminals....and the "New" Speakers located on the SIDES of the Room are labeled #4
/5, connected to L/R "SURROUND BACK" AVR Terminals.
Note in 7.1.2 (or 5.1.2) ATMOS arrangement, you have to CHOSE from among SIX different physical layouts:
[ATMOS 7.1.4 or 7.1.4 ATMOS allows you to chose any TWO Pairs of Height Speaker Locations.]
Alt-A: L/R "HEIGHT" speakers located High against the FRONT WALL.
Alt B: Your choice of CEILING location: [and you COULD drive more than one Pair of Height Speakers]
i: Somewhere between FRONT-HEIGHT Speakers and Listener, or
ii: More or less ABOVE Listener, or
iii: Somewhere between REAR-HEIGHT Speakers and Listener].
Alt C: REFLECTED off the Ceiling into Listener's Ears from a secondary Height Speaker:
i: Located on top of LF/RF Speakers, or
ii: Located on top of LR/RR Speakers.
You COULD keep the L/R-Rear-High mounted Speakers where they are now and re-connect to ATMOS L/R "SURROUND-HIGH" AVR Terminals (#7
/8)....adding a pair of L/R SIDE Speakers closer to EAR height (or even a bit lower), connected to L/R "SURROUND BACK" AVR Terminals (#4
/5). Although diagram shows them directly to SIDES of the Listener Position....that is ONLY when there is lots of room BEHIND the Listener. In your case, you likely want them about 1/2-way between Front and Rear Speakers. Note that this
Or you COULD keep the L/R-Rear-High mounted Speakers where they are now, remaining connected to
2) You COULD keep the L/R-Rear-High mounted Speakers where they are and LEAVE them connected at L/R SURROUND Speakers (#4
/5)....adding a pair of Height Speakers in whichever location you chose from the above list.
Whether you want the Height "Special Effects to whirl around the Ceiling in FRONT, ABOVE or BEHIND you is YOUR Choice.....