highlighting indepedent of lexer

I made a snippeteditor, which uses my Mergable lexer, so syntax highlighting works there (too). As you know, snippet text containts declarations independent of the tokens made by the lexer. Sometimes/often they even exists inside tokens.

To mark/highlight the declaration i was thinking of an adornment service, which independent of the tokene can highlight/select the declaration.

An other option is to let do the lexer the work, and make special tags of the declarations.

Which option do you suggest for the best result?

Thank you in advance

Regards

Martin