Wedding planner wants to bring porta potties from a different company than the ones already behind our barn. Any problem with that?

Two rental companies on one property is manageable with clear communication. The main risk is confusion over service responsibilities and truck access. Your existing standard units and the wedding planner's restroom trailer will not be serviced by the same driver unless explicitly arranged, each company handles only their own equipment. To prevent issues, mark your units clearly with your rental company's info and consider locking them for staff-only use during the event, as 120 guests exceed the capacity of two standard units. For truck access, coordinate with both companies to designate separate paths and avoid lawn damage; put this in writing with the planner. If damage occurs, liability falls to the company whose equipment or vehicle caused it, so document the property's condition before deliveries. Leaving your units in place but locked is practical, but confirm with your rental company that this won't violate your season contract.