They are not the same color dyes that color prints are made of. Sorry PAN.

The only dyes that are compatible with color prints are Kodak Retouching Dyes. AFAIK, Kodak made 3 sets. One was for Dye Transfer, one was for Flexicolor and the third was for Ektacolor. These sets had to be updated every time the papers were updated. The Marshalls retouching pencils will not fade at the same rate as a normal color print and therefore in about 10 or so years, the retouching marks will become evident.

OTOH, to answer the main question, Marshalls coloring pencils are excellent for coloring B&W prints.