The Royces don't know Lynette's family, but Bianca's family does. Geoff says that Bianca's father was the middleman in the sale of this mansion to Royce. Such houses cost a lot of money and are difficult to sell quickly, we know that Lynette's father had financial problems. Bianca's father helped sell the house at a reduced price; most likely he was a close friend/partner of Lynette's family.
In confirmation, here is this photo, the girl in the center, one of Lynette’s friends - Bianca’s mother.
View attachment 3231946
That is, the closest link to MCs family is Bianca. But how this will work outside of Jill’s path is still unclear; MC and Bianca know each other, but not so closely. On Jill's path they can be considered friends, but otherwise they only have a couple of events and a few lines of dialogue so far. Although Bianca shows interest in MC in any case.