Adding audio to a blu-ray structure

[ernnnn]

Hi!

I have been doing this for a long time until now, without problems, adding the Spanish audio to those blu-rays not edited in my country, using either Multiavchd for the whole structure or TSMuxer for individual playlists. I was so happy with it until I received my last project, the Torchwood TV series. It is the first time I'm facing a structure with sp and mp menus in the structure. When I add the audio to the files, it just doesn't work properly. It adds it, but when I try to play the structure, the new audio is not there.

I have tried to add the audio, replace an existing audio with the new one, but anyway, it doesn't work. It is the first time I'm facing this problem and it's very frustrating.

Any ideas?

Thanks in advance!

PS. I just want to maintain everything in the structure, just adding the audio. I know I have the option to create the mkv from the episodes and then adding the audio and creating a new blu-ray with custom menus and everything, but I would like to get a 1:1 copy of the original disc just adding the audio...

PS2. To give more information about the structure, there is a playlist to play both episodes and then two other playlists for the same episodes but individually.