If I understood the question correctly, you may have a recipe that makes a 1.050 porter, and you want a 1.065 porter instead? Same batch size, just a bigger beer?
I don't know of a single button to push like the "scale" button will adjust the batch size, keeping the beer the same.
If I were doing it, I would first note the BU:GU ratio, and the percentages of each grain. Then I would start increasing the amount on each grain (edit: and the hops!) until I reached my OG target, and then check the ratio and %'s to confirm I had kept the recipe in the same balance as the original.
PS: and on a slight tangent....it would help to know the hops utilization model (Rager, Tinseth, etc.) of the original recipe if you can find it. If you're copying and then changing a recipe done in Rager, and BSmith is set for Tinseth, the IBUs and therefore the BU:GU ratio will differ somewhat. You set that under Tools\Options\Bitterness.