Vision created his synthezoid wife and kids, the former being based on Wanda's brain wave pattern, the latter being a combo of his and her patterns. Tommy & Billy have met Viv fleetingly, and consider her family, albeit distant. They have little to do with Vision in the books, compared to their relationship with Wanda, FWIW. Viv also went to Wanda for help recently, and Wanda introduced her to Darcy as her daughter. Vin... uh... spoilers.