It was in The Baroque Cycle

Ah, it’s been almost a couple decades since I read the books, I imagine that time has smeared a lot of plot points from one book to the other and back again.

It was kinda cool that he recycled some family names between the stories but fifteen years on I can't keep the two straight now.

It was more than just recycling—those were meant to be ancestors of Cryptonomicon characters (except, obviously, for Enoch Root).