Honour manual changes to an overridden attribute (availability, privacy, colour)

[KrisadaFantasy]

Are you already using OGCS? 2.10.0.0

Describe the question you have

I have one-way sync from Google to Outlook calendar. It is read-only department-wide Google shared calendar with a lot of entry not involving me (but I need to be informed about nonetheless) so I set availability to free in sync option. Then I pick the one I need to attend and set it as busy and sometime with reminder in Outlook.

Next sync will rewrote it as free and remove the reminder. Is there any way to exclude specific attribute from being update in sync?