Creating additive color photographs, using stacks

[steveashby]

I have been using Photoshop to create full color pictures from B&W images (based on19th Century science). Cannot figure out how to turn off red, blue, or green, in color separations loaded into stacks with Affinity. In Photoshop, I can turn off blue and green for red layer, red and green for blue layer, and blue and red for green layer. The result is a color image.Have attached screen shot of dialog box that allows this in Photoshop. Is there a simple way to do this in Affinity? Thanks!