The comment in grpinfo.txt is a bit erroneous so I'm sorry but you'll have to forgive me on that one. I'm also confused how the engine can load a GRP file from a somewhat absolute path ("addons/dc/dukedc.grp") but couldn't load a CON file called in the same way.
Regarding loading from 'addons/<name>/<name>.grp' within the running directory of Raze, that's not something EDuke32 does anyway from my testing. For drop-in replacement, it's probably better to maintain compatibility, unless you're trying to promote a different way of organising grp files?
The functionality is important to me because I use '-addon [0-3]' (or could just use '-gamegrp <name>.grp') in scripts that just load the game and add CON/DEF files as necessary. Right now neither way works, it can't find the specified GRP file so it askes me what to select at start.
Absolutely not trying to be confrontational, just trying to assist in solutions and thought what I found might be viable and save you the grunt work considering all the other important stuff that's going on.

The comment in grpinfo.txt is a bit erroneous so I'm sorry but you'll have to forgive me on that one. I'm also confused how the engine can load a GRP file from a somewhat absolute path ("addons/dc/dukedc.grp") but couldn't load a CON file called in the same way.
Regarding loading from 'addons/<name>/<name>.grp' within the running directory of Raze, that's not something EDuke32 does anyway from my testing. For drop-in replacement, it's probably better to maintain compatibility, unless you're trying to promote a different way of organising grp files?
The functionality is important to me because I use '-addon [0-3]' (or could just use '-gamegrp <name>.grp') in scripts that just load the game and add CON/DEF files as necessary. Right now neither way works, it can't find the specified GRP file so it askes me what to select at start.
Absolutely not trying to be confrontational, just trying to assist in solutions and thought what I found might be viable and save you the grunt work considering all the other important stuff that's going on. :)