If the trust is governed by Michigan law the Michigan Trust Code imposes several duties on a trustee. One of the many duties is to keep the qualified trust beneficiaries reasonably informed about the trust administration and the material facts necessary for them to protect their interests..
The MIchigan Trust Code goes into great detail defining the trustee duties and the consequences if the trustee breaches the duties.
The trust is not recorded but it can be registered and the registration process is set forth in the Michigan Trust Code
From your description, it sounds as if the beneficiaries asking for information are contingent beneficiaries, and likely are not entitled to any information until the grantor passes away. However, it depends entirely on the language of the trust. You may need to consult with a probate attorney to determine your responsibilities at this point or decline to act as trustee if you don't know what you are supposed to be doing. The attorney fees for the trustee are to be paid out of the trust, so you shouldn't have to be out of pocket for advice.
It is true that the Trustee must keep beneficiaries informed, however only current and not contingent beneficiaries. That Trust is a contract between you (and the other co-Trustees) and the Grantors (Owners) and subject to Trust code rules, the terms of the Trust state your obligations. If the Grantors are still living they may be the only current beneficiaries and letting contingent beneficiaries know their business would likely breach the agreement.
MCL 700.1302 gives the probate court exclusive jurisdiction over trust matters. MCL 700.7202 provides that the trustee submits to jurisdiction in the probate court in the county where the trust is "registered." Many trusts are not registered. The trust may also provide where it is supposed to be registered. MCL 700.7209 provides for the venue where a trust may be registered.