There are too many imprecise terms being used, and you want to use VERY precise words or instructions will be hopelessly confusing.
"File" is very different from "folder", yes? But you write "I have a file and within that file there are 4 other files.
Do you mean, "I have a Folder that contains 4 sub-folders - Folder One, Folder Two, Folder Three and Folder Four"?
Or do you actually have a huge 30Gb File, perhaps with an .ISO suffix, and within that file, you see 4 other smaller ISO files?
Then, under each of there, are two sub-sub-folders called AUDIO_TS and VIDEO_TS?
(AUDIO_TS folders are normally empty, by the way.)
The VIDEO_TS folder (that Underscore is important, by the way) will be filled with 7-8Gb of files, as you wrote for a total aggregate of your described "30Gb". Yes?
Probably, you want to know, "Can I combine these four folders' worth of files into a single Playable Folder on the BluRay, or do I need to leave them as the four separate 'folders'?"