Unfortunately, this is Edge limitation. However, you can workaround this with virtual things edge driver.
Install virtual things edge driver
Create virtual switch
Create 2 automations
3a. If virtual switch is on - turn on switch X on multigang switch
3b If virtual switch is off - turn off switch X on multigang switch
Do not use toggle option in automation, it might not work
If you need a feedback for the gang status for your virtual switch, create another 2 automations for the same gang
I realise that creating 4 automations manually for each gang is a lot of work, but this is what we currently have.
Regards
P.S.
Below is the link to my virtual things driver, but you can use any virtual switch (DTH or Edge) to achieve this