Update all groupappointments

We're using Office 365 for appointments (outlook) and we're able to make group and group appointments and this for a long period of time (from days until several month (up to 9 month)). 

During time these groups changes a lot (new people, people leaving etc) and instead of changing all these appointments manually we would like to change the groups and and update all the corresponding appointments. Is this possible and if so can you explain how to ?