CHAINing Weights

For a mod I'm working on, I have to use a weight to edit the dialogue (Can't use implicit ordering because it's modifying a Bioware .dlg and I want it to fire before any of the other weights.) What I was hoping to do was this:

CHAIN
IF WEIGHT #-999 ~Insert conditions here~ THEN ~d-file~ TalkChain
~Dialogue of first speaker~
DO ~SetGlobal to prevent repetition~
==Custom NPC File
~Response~
==First
~Response~
EXIT

Is my format there correct? If it's not, could someone please give me the correct format?

That should work, yes. Although it looks like you don't have a space between == and the DLG name.