How do you color balance two photos to 'match'

I've got two different color balance problems.

the first is where I have two photos that I want to match the lighting in each.

The second is where I have a 'control' and I want another photo or print to 'match' it.

Currently I'm having the second problem. A customer brought in an original painting for us to scan and make holiday cards from. But they also brought in a photo print from a local chain and they have asked me to match the color representation from that print.

It is duller, the blues are purple and it is over all darker. Personally, I think the photo is a horrible representation of the painting. BUT IT IS WHAT THE CUSTOMER WANTS. GRRRR.

I've scanned in both the photo and the original drawing. If I print the photo it matches the color of the scan. (but is the wrong crop size and can't be used for the card.)  How do I draw color out of that and get my original to 'match' other than just using my eyes? (which is about impossible for me today) I normally use 'sample/target balance' in corel PhotoPaint, but you can't do that between two layers OR between two files. This would be a great change to make in x7 or an update.