I think the key is remembering to "Add Invitee" for new appointments.
I have gotten into the habit of doing so for all non-business appointments, even if the appointment is not for the other person (e.g. the wife), but by using keywords to identify whom. So, if I have a dentist appointment, then in the subject I might show "Klotar: Dentist Appt" so that the wife doesn't think it's her appointment but will still be aware that I have an appointment.
In your case, just remembering to Invite Attendee for the kids stuff will take care of the reminder issue. Just don't invite her for the non-kids stuff.
Sync'ing with Outlook or DM isn't an issue, the wife never syncs, I only do so weekly.
Supervising Manager of the Department of Redundancy Department.
BlackBerry Certified Support Specialist