priorities with Descent2 HOG files

[Christian]

Hello

I am working with the modified Descent2 source D2X and I am pretty new
to PhysFS so I need to ask this here.

I am currently fighting with the priorities of the HOG files when custom
content should be loaded.

Example:
The main file of Descent2 - descent2.hog is loaded at init or Program
and as far as I see it mustn't be closed until the whole game quits.
In this example this file has a Music track within called game01.mid

Now I load a addon mission, with custom content (by adding to search path).
This file ALSO has a (modified) game01.mid which is not used, the
game01.mid from descent2.hog is used for this.

I had the approach to remove descent2.hog from Search path, adding the
custom file and then adding descent2.hog again to switch the priority
for this files.
But this wasn't very reliable since while this happens, there could be
opened files within the descent2.hog which fails removing it from search
path.

I have digged through the PhysFS doc very closely but I haven't found
anything yet.