Move Colour Art into Line Art (&vice-versa)

Forgive the short fuse, I have lost 3 hours of productive time wondering why some items of my puppet were hard to select and another 3 trying to figure out a way to move what has been created in the Colour Art layer BACK into the Lineart Layer.

No doubt when pressing K to show lines I touched the L key and it switched me.

Now my puppet is cut in half between Line Art and Colour Art.

IS THERE A WAY to bring what is in one back into the other WITHOUT having to do it cut-and-pastey frame by frame, exposure by exposure?

The forum search yielded nothing and the helping documents really don’t deserve their name.

Thank your for your time.

From the drawing menu you have the option to “Create Color Art from Line Art”
but the opposite functionality does not exist. I hope this will make it easier to fix.