IMHO, I think you've got to keep smiling and talking to everyone even in the middle of picture taking, Les.
With years of experience, you should be able to change the settings while in conversation with someone.
The mood of a room could change when they think, "Oh, we've lost grandpa, he's into being a photographer again."
If you feel responsibility to get worthy shots, that anxiety will just be transmitted into everyone around you, in what's supposed to be a joyous occasion - there should be natural smiles on all the subjects and everyone in the background.
Concentrating on rapport rewards us, all the technique and gear we should have sorted out a long time ago. The camera can stay low on its strap, smoothly up for a couple of well-chosen frames (key moments like people leaning over to greet the baby, the baby being picked up by the mother, etc), and smoothly back down again to defuse the tension. The longer you point a camera at someone, the longer they're under strain, and after a few seconds, you're getting an endured pose, not authentic expression.
There's less need to play the stealth card, you know all these people, you've put up with them over the years and they've put up with you, you can get some fantastic intimate photos by being close and upfront, instead of the paparazzi sniping with a long lens through the living room window.
An excuse for me to go with my own grand daughter here, using the K55 f1.8: