I'm American and I wouldn't do this, unless I had just introduced them. I assume the OP is referring to situations where the introduction of the names, if it ha

I'm American and I wouldn't do this, unless I had just introduced them. I assume the OP is referring to situations where the introduction of the names, if it happened at all, was a long time ago. In that case, I would argue the etiquette should be the other way: it seems slightly inconsiderate to assume the listeners have committed your family tree to memory if they've never met them.