Wyze devices can’t be in two separate groups at the same time. They can only be in one group and they can’t be subgrouped.
I just thought of a simpler way without modifying the 4 bulb group: just create a second schedule rule for on at 9:51pm off at sunrise and select the individual bulbs 1 & 2 as the devices, not the entire group. Otherwise
You will need to remove bulbs 3 and 4 from the 4 Bulb Group and create a Bulb Group B, renaming the original group Bulb Group A (bulbs 1 & 2). Then add Bulb 3 and 4 to Bulb Group B.
Go to the original schedule rule for the 4 bulb Group “On at Sunset”, and modify the Devices so that it reflects the same command (I assume you use Turn On) but you will select two device groups: Group A (bulbs 1 & 2) and Group B (bulbs 3 & 4).
Create another rule schedule rule for on at 9:51pm off at sunrise but only select Group A (bulbs 1 & 2) as the device.