Creating a multi-channel PNG from several single-color PNGs (by channels) Where to dig?

Question

Graphic arts

Good day to all.

Generally the vector in which to me to dig the information interests.

Similar to working in FS.
There are several PNGs in Grayscale.
Using the multi-channel format, we can assign a color to each channel, and as a result, the original file is imitated using color overlay. that is, the channels can intersect with each other.

I understand how to assign the desired PNG color. I have no idea how to blind 5 PNGs with different color data so that they overlap each other to give the desired color (more precisely, the correct one).

How to blind a PNG that does not overlap - I know.

Figuratively, it is necessary to make a website constructor that will change the colors of the final images depending on the list and the order of colors using the PNG list.