You cannot control another person’s integrity, but you can control how long your decisions depend on it.

You cannot make someone honest, and trying is a poor use of your time. What you can decide is how much of your position rests on their integrity, and for how long. That is a design question about your own arrangements rather than a moral question about them.

Look at where you are exposed to someone else’s character and ask whether the exposure is necessary. Reduce it where you can: shorter commitments, clearer terms, alternatives in place. Trust is fine; total dependence on it is a structural risk.