That's not something the Calendar in TouchSmart supports.

In my experience, most calendars that you can sync keep the data for each calendar separate in order to reduce the complexity of merging/splitting events. In Windows Calendar, for example, you can create several separate calendars (one for each family member, for example), and the Calendar application will then show them all together in the same display area, but they will still be distinguishable as separate calendars.

As long as the calendar displays events from both sources, that should suffice, I would think.

That is a suggestion that can be taken into consideration. I'll see if I can pass it on to the team in charge of the Calendar. For now, it's not something the software can do. Sorry.