Staked players in a game with the staker

[SA125]

I posted this in the Poker Theory forum but wasn't sure whether or not that was the right forum or not. I'm putting it out here also because this forum was my first thought for where the question could best be answered. I'm hoping the sharp guys here can recognize something in it and offer something tangible.

The scenario is this. I play in a full ring game where one of the players sometimes has a piece of numerous others in the game. The staked players varies from one to three and the piece he has of them varies from 25-50% to maybe 100% of one of them.

Forget about possible collusion. There's definitely soft playing and the potential is obvious but isn't part of the question here.

Is it possible to look at this scenario strictly from a math/EV gambling standpoint and see whether or not the staker has an edge in this game?

To break it down further you can take a typical 3 way pot and say it's a 3 handed game where it's you, the staker and the 50% horse. The horse is playing legit and trying to win. Does the staker have an edge in those scenario's?

All comments appreciated as this is an actual scenario in a live high stakes game I've played a lot in.