Many of the scenarios have two blip reinforcements, so for a two-man Genestealer team, each player could receive and control one blip, and all of the genestealers that are created by those blips. It'd be up to those players to keep track of which models are whose.
Since there are only a few sculpts for the genestealers, each player could claim one or two specific sculpts, and only play with those models. Or, you could also use those really cheap plastic poker chips that come in either blue, red, or white, and slip a colored chip under your model. And each player would have a different colored chip to mark their models.
sounds quite legit i ll give it a try