How do i wire 2 amps together

Good morning Audiophiles. I NEED HELP! So i am trying to set up set up a Home Theatre and i think i may need a second stereo amp to drive my centres, but i want to connect with people who have this set up to explain to me how this can be done. This is my scenario: I have the Onkyo TXNR-1030 (9.2 channel). I have a Boston Acoustic (BA) VR Centre, 2 X BA VR3 Reference floor standers, 2 X Pioneer SRS88TB side surrounds, 2 X BA VR3 Reference Dipoles at the back, 2 X Onkyo Atmos for front heights and in the ceiling a pair of Yamaha NS-CI800. Subs are BA PV800, and Yamaha YST-SW320. I also have a KEF Centre T301C (for Netflix etc.). So i want to have a 7.2.4 set up as this would work in my space. Now the AV Receiver only drives 11 channels (at 75W RMS, 8 Ohm), and rather than driving my Atmos speakers, i was wondering if it were possible/how to drive perhaps my centres and the Centre KEF with a 2nd stereo amp? How are the two amps connected to synchronise? Is this a master/slave scenario? Your advice, as well as links to how this can be done would help. Am finding forums online but nothing that drills down to basic level of how this is wired to be done. I am no techie, and a beginner in this space so i would appreciate the dumbing down approach. Thank you for your advice...