Is possible to use different cards in nDisplay mGPU feature?

I’m in commercial production using two A6000 NVLink system. but the slow performance of the A6000 is problem, so we are testing the mgpu in RTX 3090 with A6000.

the A6000 is needs to be use because to synchronize the LED outputs by connected with a Quadro Sync 2

By this doc, it says possible to use mgpu without NVLink (and I know that NVLink with 3090 and A6000 is not work)

I’ve tested all possible mgpu settings in switchboard and ndisplay actor in all possible cases, but after the first successful test, it didn’t work the next day. ( I can’t sure the first test was goes correctly but performance was great like run project with single rtx3090 )
so I think that it is possible and I am testing it.

Also tested r.GraphicsAdapter option but it seems not work and UE is always uses displaycable connected GPU cards.

The real question is:
Can RTX 3090 with A6000 work with nDisplay?
Is it possible to synchronize LED displays without A6000 and Quadro Sync 2?
I want to use the performance of the RTX 3090 with the synchronization of the Quadro Sync 2. Is this possible or is there another way to achieve a similar level of synchronization?