Is it possible to restrict a component ...

[Rollo]

How does the whole "Family" thing get created? Can I just pull out any number I want? I just have to make sure that it doesn't match any other family numbers being used.

'Comp Family Requirement := ' is an optional line in compenhancement.txt. As for the family numbers themselves, I took the 3519 from your posted component. Yes, you can use any number you want (probably between 0 and 65000). And yes, you definately want to make sure only same components and their higher tech variants share the same number.

Any ideas why the Aux Control didn't work?

Nope, not a clue. When come to modding it usually better not to ask these questions . Try what works, use it if it does, look for other option if it doesn't. I usually blame the prgramm code and move on =).