The same recipe brewed on different systems will yield different results. You and I could both brew the same recipe using the same equipment and not end up with the same results. Using different equipment can greatly increase the differences as well.
The first thing you need to do before using BeerSmith is set up an equipment profile to closely match your system. I believe there is a profile for the Grainfather available using the add on tool. Don't assume that the add on profile will match your Grainfather and your style of brewing. Follow the instruction in this video:
https://youtu.be/QmW7pwQP5mQOnce you have tweaked the profile as needed, keep notes for the first few brews. You may need to make some minor adjustments to dial it in, based on your results.
If you use a recope found on BeeerSmith you can use the scaling tool to adapt the recipe for your system. If not, you will likely need to make some adjustments in order to match gravity, color and bitterness. Keep in mind that the beer you brew either way may not be the same as the original due to subtle differences in ingredients and your techniques.