Hi, I think there's an issue with XBVR where the script files are always sorted based on date modification time, rather than the order that you add the files. A workaround is to open the file in notepad, change some stuff (and change it back), and then resave to update the file modification time.
XBVR doesn't provide video filenames to HereSphere, so there isn't a way for HereSphere to match it to the script, except based on the order that the videos and scripts are supplied to HereSphere. Multipart videos use a hacky method of overriding the encoding streams to provide multiple videos for what should be a single video.