How do I repeat an event monthly and have the event deferred to the previous Friday if the event falls on a weekend.

Company is paid twice a month. The 15th and the last day of the month.

Setting the last day of the month would be repeat every month on last weekday. But how do you set the 15th with these conditions:

If the 15th falls on the weekend, it will be the Friday before the weekend. For example, 15th of May 2016 falls on a Sunday, the event should be moved to the 13th of May instead. Is it at all possible?

Thanks!