I already tried naming them (like in "Fallout 4/Data/Fallout4 - Textures1~9.ba2")
MyTextures - Textures1.ba2, MyTextures - Textures2.ba2, MyTextures - Textures3.ba2, MyTextures - Textures4.ba2, MyTextures - Textures5.ba2, MyTextures - Textures6.ba2, MyTextures - Textures7.ba2
and the plugin is called MyTextures.esp (an empty plugin made in CK), but the ba2 are not being loaded (I'm using MO2 btw), I also tried adding the files into Fallout4.ini but then those were the only files getting loaded.
Maybe I could use existing plugins? For example "existingModFromNexus.esp" and rename the ba2 as "existingModFromNexus - Textures.ba2", would that work?
I can't merge the archives (filesize would be too big, they are retextures) so I guess I will have to make a plug-in for every ba2 archive, though that would defeat the whole purpose of making ba2 archives.