How do I add numbers/counters to recurring appointments
 

I use a lot of recurring appointments to keep tabs on the freelancers who
work for me.
My scenario is like this:
1. John works for me every Mon, Wed and Friday.
2.Mary comes in every Tuesday.
They both bill me at the end of the month and they charge me per day.

Is there any way to get outlook to read the number/counter of the recurring
appointment, so that I could just know their number of sessions at the end of
each month?
It would be great for overall billing as I would know that by the end of
October Mary had 28 sessions with me.. 32 at the end of November and so on
and so forth.

Pls help.