Using xLights and Vixen 3 on same project

[algerdes]

Until now the projects were separate.  We use xL/NC on one, and Vixen3 on the other.
Now we want to use both (different mindsets) on the same project.  The question we need to discover the answer to is:

In V3 we have channels assigned to each controller (there are 9 of them).  There are spare channels assigned to each for expansion.  (e.g., 192.168.2.207 has 3072 channels assigned, but only uses 2892 at this time.)  In V3 we simply put in a "channel count" as part of the configuration.  I understand that the non-used channels (180 in this case) are just padded with zeros when the FPP output is made in V3.

How do I setup xLights to account for these empty channels?

[algerdes]

OK, I'm beginning to understand a bit better.
Please let me know if I'm missing something:

In the setup tab, each universe (with appropriate # of channels for the controller) will be processed.  e.g., I have 5 universes @ 510 channels which means 2550 channels will be assigned and put "on the line" when the sequence runs.  Even if I only fill 2493 of those channels, the remaining 57 will be in the stream and filled with zeros (or something relevant).

The next controller, with its associated channels then will follow - same scenario.  Its starting channel will be 2551 and run through - let's say 3570 channels - though only 3069 are being used.

My confusion began while watching Sean's video about setting up xL/NC and his spreadsheet keeping "start channels".  Being a "starters tutorial", there wasn't any mention about the empty channels in the spreadsheet.

I think I have it, but don't count out any further questions.