This might be a simple fix with something I'm missing because I'm fixated on the problem and learning how to use a SmartFade 1296 for the first time. I need to patch in four LED Flat Tri Par 18x units, in DMX mode (5 channel) but I'm having trouble understanding how to assign them multiple DMX channels on the board so I can color mix and control the intensity. The language around patching doesn't seem to allow this? The space uses Elation DP-640 dimmers, I'm not sure if the way they've been assigned addresses has anything to do with this or not but maybe its worth knowing.
If I understand you well, you can't do that. It doesn't understand multi parameter fixtures, it's based around dimmers.
Words first! Your fixtures are set to a "starting address" and therefore listen to that and the next 4 "addresses". It uses those to control "parameters" such as RGB colors, strobe, master intensity or whatever. The board has "channels" or faders that can have one or more addresses assigned to them. Using the word channel for everything is confusing.
The 1296 does single or group addresses per channel, but they are all at the same level. With a 5 address fixture you control each address individually. so Fixture 1 would be channels 7-11 (after the dimmer pack?), fixture 2 at 12-16, etc, tracking with their DMX addresses. You can patch the fixtures together, or just address them the same to control them together.
If you get really tricky you could group some of the 'special' parameters together so save channels, but that's getting into advanced stuff and would only fit some shows. Smarter "Moving Light" or LED consoles (i.e. SmartFade ML) do things very differently and make complex lights much easier to handle.