Preventive maintenance using factory calendar as wel as reference date

Hi, I hope someone can help me with the following. We have a maintenance plan setup for an equipment and we would like it to generate a workorder on the 15th of each month (using a cycle of 1 month), excluding May u/i August. A factory calendar has been created to exclude these months form the working days. However, if we select this factory calendar on the maintenance plan and select 'Time - factory caldr', orders are not generated for the 15th each month of the factory calendar, but every 30 days (as expected) in September u/i April. If we select 'Time - key date' on the scheduling indicator, we do get workorders every month on the 15th, but also for the months we excluded in the factory calendar.

Is there a way to have both? So on the 15th each month in September u/i April only?

Looking forward to your reply.

Kind regards, Jelle.