Replacing audio & editing menu graphics w/o re-encoding

[JediFonger]

howdy! long, long time AV-enthusiast/HTPC user, first time posting. sorry if i posted in the wrong group, admin/mods please move to whichever one is the most appropriate.

my goal is to replace blu-ray audio with Atmos tracks. for example, i bought and own Gran Turismo 4k package and of course Atmos is only on the 4k disc and blu-ray does NOT have Atmos.

in general, i've been using this process:
http://forum.doom9.net/showthread.ph...87#post1650887

it seems to be fine to keep the menu and you can have the Atmos, but the OCD part of me wants to get a little crazy and try to edit the blu-ray menu so the language/audio will mirror the 4k disc with Atmos option.

i know, i know, it's pretty stupid, just be happy with the movie or use mkv blah blah blah... but i do think a core part of forums like this is to BE that ocd >P.

https://forum.doom9.org/showthread.php?t=152952
^but it appears to require scenarist and etc. tools.

so my question is, is it possible to edit blu-ray language menus WITHOUT those expensive tools? in another words, can this even be achieved w/multiavd/bdrebuild or somn.

i know there's a huge variety of methods retail blu-rays are authored... but in my monkey brain, i just think it's as easy as editing some png in jars folder? is it really that easy? i haven't even attempted because i just want to know if i can do everything with just free open source tools.