The Manager cannot change the motion. The Minutes are a legal record of the meeting and the motions which passed.
If the contract has different terms, then that may create a conflict however the manager CANNOT knowingly change minutes to a set of events which did not happen. That is very illegal and you should be seeking legal advice on this.
The minutes under the various state acts must be an accurate representation of the meetings and the motions which passed. The manager or chair cannot retrospectively change those.
The manager can challenge the motion with the committee and the OC but cannot change and given the contract term gives the manager a financial benefit likely puts them in breach of their duty to act in the best interests of the OC as there is now a conflict of interest as well.
If any manager does this, the OC should be seriously looking at terminating the contract and looking elsewhere as this is a fundamental breach of trust, and of their duties as the manager on behalf of the OC.
They are clearly putting their own interests above the legislation and their legal responsibility to reflect the minutes.
The first thing the committee should do, is write their own minutes distributing them and disregard the managers minutes as not being an accurate reflection of the meeting.