How to Script copy+paste a grayscale layer into Channel with Scripting?

Please explain the process more clearly, ideally post the images or at least meaningful screenshots including the pertinent Panels. 

An RGB image can obviously not contain a grayscale Layer so how many files are you talking about? 

How can the corresponfing files be identified – is there a naming convention? 

Edit: Should have refreshed the page before posting … 

The forum needs to understand the file and layer structure.

Is the source a separate file? Is the destination a separate file?

Or a single file?

How many files may be open at a singe time? Will you be working on other projects at the same time, or will only the required files be open for this task?

What colour mode are the source and destination docs? Grayscale or RGB? If the source layers are "grey" then can we presume that the RGB channels are exaxtly the same for the sourxe file (R=G=B)?

You don't mention the B channel.

Can you show cropped screenshots of the layers panel for the source and destination files, as well as the channels panel for both files? Can you provide sample files?

Will channels always have the same names? What about the layers? What about source and destination file names?

You know the files and workflow, others don't.