I don't think we've ever seen those four together in one place. There were rumors that they knew each other. But I don't think so. Possibly because of the cameras, but rarely do you see guests in their apartments. Maya would have girls visit (other then her sister) but that was usually for a dye job. Leora has one girl who sleeps over every few months (probably lives far away). But other then that, nobody visits them (I get the impression Leora & Paul are not social butterflies as rarely to they 'dress up' when they leave the apartment together).
Someone mentioned that Leora has social anxiety. Unless he/she understands Russian, not sure how he/she came to that conclusion.