No other Corleone caporegimes are mentioned either in the novel or in the film. Sonny had his own regime.

The statement that Clemenza made about Tessio and he forming their own families probably was predicated on either Vito's retirement or death. I don't think Clemenza implied that there'd be a Corleone Family in addition to his and Tess's families.

Solozzo was, technically, a free-lancer--a big-time European drug wholesaler looking to get a foothold in America by allying himself with Tessio. But definitely a "man of respect." We've speculated here about what might have happened if Sol had succeeded either in convincing Vito to support him, or in killing Vito and making a deal with Sonny. My guess is that he'd probably become a caporegime under Barzini.