Hi Carol
There isn` t a practical way of scaling tool paths in only one plane. I`f you have scanned in a 3D model then i would use that to create the various sizes that you require and create a bespoke programme for each size.
Scaling tool paths are something i would personally avoid as it is likely you will get unecpected results , where as by using individual models keeps things tidy and less likely to cause problems.
I hope this helps.
Kindest regards.