Synchronisation of 2 Multiflex devices?

Hello to all,
I use a Flex6400 in the Shack and also have a Maestro there. I do a lot of contesting and the audio delay between TX and RX of about 0.5sec on the Maestro is very hindering for fast operation. I therefore operate the microphone and the PTT directly on the F6400, as there are then no delays. However, I would also like to use the advantages of the Maestro in terms of operation. The device simply feels good with its buttons and keys and it's fun to contest with it. But as soon as I have SSDR and the Maestro in operation, the two form separate virtual devices via Multiflex. But I don't want it that way! I would like to operate the Maestro, but use the microphone and the PTT on the F6400 because of the low delay. Unfortunately, I can't find a way to synchronise or lock the two devices so that I can, for example, change the QRG on the Maestro and this is then also done automatically on the SSDR. Is there any way to set this?

73s de Tor, DM1TS