Education & Career

Should I encourage my employees to speak up?

I am a supervisor at a local church and oversee a group of women who work in the nursery.
The church I work at has an issue with an outside group who doesn't pay their bills. However, the church is unable to "kick out" this group as they were grandfathered in by the previous pastor. Since the group doesn't want to work with the church and make payments, the church has assigned a few people to help slowly move these people out (example, they are using our cabinets to store their items. They'll have to move those out by May or pay since that wasn't part of the original contract). It's a small group of 4, including me. The main guy in charge is collecting statements from the office staff who have has issues with this group in the past.
I have had my fair share of moments with this group so I can honestly say that they are a bunch of arrogant a-holes. However, the group of women I oversee told me a few months ago, that before I came here, this group stole items from them. They were given a bunch of toys and high chairs from an elderly lady for them to use. One day, they came in and saw they had gone missing. A few weeks later, they saw the outside group using them. They informed their then supervisor (who is now my boss) who just said, "Oh that's too bad."
Well they brought it up again to me recently. With everything going on, I really want them to speak up about what happened to them. My only concern is that 1) they don't have physical proof that they stole it, 2) any comments they make might get my boss in trouble (I don't care for them much anyway though, but still) 3) I am almost worried it might look fake.
Should I encourage them to say something or leave it alone?

Should I encourage my employees to speak up?
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