Just go with the fiance and how great she is. Try not to force the two families together too much. I think a lot of the family problems through marriage would do better if the two parental couples stayed pretty separate, only joining up when absolutely necessary. I’ve witnessed some marriages where they jolly-forced a lot of togetherness between the two families and it just doesn’t work. Best to spend holidays etc separately and join up only for those events like the grandchildren’s birthdays or sports. For some reason, those marriages have less trouble between inlaws.
Congrats to your boy. Hope all goes well for a lifetime.
Thank you for your kind thoughts and well wishes.