Welcome abooth1. We've always had dogs, but grandchildren only appeared 6 years ago. Whippets are known for their gentle dispositions, but beware they are rescue dogs. You don't know what they have been through. Take it very carefully at first. It also depends on the age of your grandson, but if he is the same one who helped you get on Gransnet then there shouldn't be a problem.
As granjura said keep an eye and NEVER allow your grandson to put his face close to them or to try to outstare them. Get him to give them tipbits and their dinner if at all possible. This will establish in their minds that he is higher up,the pack order than they are. Don't let them barge though doors ahead of you or your family. And give them plenty of exercise. Finally never, ever hit or smack them for my reason, use you voice to discipline them. Even better take thm to doggy training classes, you'll make new friends and learn so much.
Enjoy your new additions. 