Heather D. answered 12/09/20
If I am understanding your question, you've created a logo where elements are at 60% opacity and want them to appear that way even if the logo gets put on let's say, a black background. Basically you want to make a white shape and put it behind the logo and group it so that wherever it is used, it has that white so that it reads how you want it to.
The way I would do it is group your whole logo, then Edit > Copy > Paste in Front (command / control–F). With the top white logo shape selected, go into the Pathfinder palette. Select Unite Shape (first row, top left). This should create a single shape of your logo. Fill this shape with white.
Cut the logo (command / control–X), then paste in back (command / control–B) of your desired logo. This should place the white logo exactly under it. Group them all together so the elements don't shift.
Your other option is to make a copy of the artwork, go to the top menu and select Object (or Flatten Transparency), and eyedrop the 60% area. Add that color to your swatches and replace the transparent color areas with the eyedropped one, so they will be a 100% color when printing. Hope this helps!