Creating new event in shared Google calendar

[vanj]

My son has a Android 2.2.1 on LG Optimus V. I have created a Google Calendar for him on my Google accoount and given him full access to it under Shared/Settings. Using the native Android Calendar app on his phone, he can edit and delete events from this shared calendar.

Question: When he creates a new event, it is created in his personal Google calendar. How can I set things up so any new events he creates use the shared calendar?

Thanks