WeiDU parsing: issue with require_predicate or component

I'm trying to link certain components with ADD_KIT that are necessary for the custom kit. I'd like to install these components only if the kit was installed, but the way it's set up right now, these files will be added regardless of whether or not the kit was added. I get parsing issues if I try to add lines (i.e. COPY ~whatever~ ~override~) between BEGIN and END of ADD_KIT.
I'm trying something like:

BEGIN ~X~
SUBCOMPONENT ~Y~
REQUIRE_PREDICATE ~Z~

But this is where I'm lost. I don't know how to use REQUIRE_PREDICATE (or COMPONENT) other than for GAME_IS, and I'd really like these components to always install with the kit and not give a choice, seeing as they're necessary for the kit to work.

How do I use WeiDU to check if a component is installed and then automatically install a corresponding component? Thanks!

P.S. I've got Bladesinger and Priestess of Lloth kits complete now, just need to polish them up before release. I really appreciate any help.


Edit: not sure if I got it or not.
I used:
ACTION_IF FILE_EXISTS ~override/EMCLABLL.2da~
THEN BEGIN

I'm just not sure if ADD_KIT adds the custom CLAB file that you indicate the class should use.