Gtags argument forwarding to plugins

Hi
I use Global with Universal Ctags plug-in to index C++ code. Universal Ctags has command line arguments to skip or define macros (-I or -D).
However, Gtags is used to invoke ctags internally, is there any way to forward arguments from gtags to ctags or a plug-in in general? Is there an environmental variable which does that? I went through Global’s manually thoroughly but couldn’t find anything. I think GTAGS_OPTIONS is only to give it to gtags not to the underlying plug-in/parser.
This feature will be a useful addition to avoid issues like this.
   
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What is your environment (OS)?
      
      - Linux and macOS.

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Which version of GLOBAL are you using?
      
      - 6.6.4


Thanks!
Sundaram
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