Is it obligatory to inform other partners about grants offered by one of the partners to attract customers?

The manager and partner are trustworthy and are not held liable. Their actions are presumed to be for the benefit of the business, unless they violate the partners' conditions. Therefore, if what the manager provides to craftsmen and others is for the benefit of the work, it does not depend on the partners' knowledge unless the partnership contract stipulates otherwise. Muslims are bound by their conditions, unless they contradict the Sharia.