Microsoft Tools for Small and Medium Businesses AMA

I can't make the session but hope you will consider my question. Like many microbusinesses I work with clients who give me access to their 365 environment. And that creates a second calendar. My client can see that calendar, but it looks empty because all my appointments are in 'my' calendar. I need to reflect my free / busy in the calendar my client has set up to ease meeting booking etc. I have found no way to do this. Giving access to 'my' calendar is not a feasible option. By 'my' calendar I mean the calendar in my 365 account.