How to import multiple images for UV editor

I have tried to put multiple textures to the Object with the UV map as shown in the attached image. There should be three different textures to be used, but I can only load one as shown. I have tried to use Image Sequence and UDIM tiles type but it gives back “Can’t load image” error.

What should I set up to load multiple images? Should I rename the files with the same name and a number behind it? Thanks for helping me. I don’t want to change the UV map and textures as it is done already - I just need to know how to map the given different textures to the SAME mesh.

The UV coordinates are easy to be set in 3ds Max with a specified user input box for it, such as U:1 V:2 - But I cannot find the same interface in Blender. Do I miss something here?

I want to know more about UV channel and texture painting in Blender with multiple texture files on the same mesh. Thanks again.