You can lay out the channels and zones however you want.
In the CS750 programing software, you have one section where you first define or create the channels (frequency, offset, FM, CTCSS, digital, color code and all that stuff) Once done you assign those channels you created to zones.
A zone is just a group of up to 16 channels. You can put whatever you want in a zone. In the section where the zones are programed you get two columns. One has all the channels that have been defined and the other is a list of the zone members.
The zone member list is blank at first.. You add to the zone member list by moving up to 16 of the channels you defined over from the available channel list. They can be digital or analog.
You select the zone via the front panel menu. You select the channels in the zone using the 16 position dial on top of the radio.
What you add to each zone is up to you. One of our local DMR repeaters only has 3 slots that are commonly used.... So, I added a couple of popular FM repeaters to that Zone. That way I can use the top dial to switch between Digital and FM without having to go into the menu to change zones.
Out of interest, I also have a Motorola XPR6550. It's programed a little differently with the CPS software, but you can have FM and Digital in the same zone.