In older versions of Minecraft, it's literally impossible to use more than one texture pack at once. We could have a special version of Pridepack and PrideGUI that are merged with eachother.
This applies for all versions since the first one that supports texture packs, up until 1.4.5.
We'd either need a new branch, or a new repo for the GitHub version of this, and
We'd need two extra projects on Modrinth for PrideGUI Legacy Dark + Pridepack and PrideGUI Legacy Light + Pridepack