Hello gemstone and welcome to the Palm forums.
It looks like you are correct, The Missing Sync won't allow you to set their implementation of the conduit manager to allow the PDA to overwrite data on the Mac; according to part of this HotSync troubleshooter I was reading. It states:
"When you look at the Sync History log and see that there are no errors in the log, but find that the records did not sync as you expected, there are a number of possible reasons.
1. Conduit configuration. Go to Missing Sync, double click on the conduit:
- See if it is configured to 'Synchronize' or 'Overwrite handheld with desktop data'.
- See if it is set to sync all calendars/groups/categories or selected calendars/groups/categories (depending on what plugin you’re looking at.)
- With the Mark/Space Events  and Mark/Space Tasks  conduits see what calendar is used for the option "Put items from 'read-only' calendars into". Change it if necessary.
- With Mark/Space Events check the setting for "Ignore desktop events older than:"
- With Mark/Space Tasks check the setting for "Ignore desktop tasks older than:"
- With Mark/Space Notes conduit verify which application it is configured to sync with: Mark/Space Notebook, Microsoft Entourage, and Yojimbo (1.3+)"
Without contacting Mark/Space, you may need to uninstall the Missing Sync and reinstall Palm Desktop 4.2.1 Rev D for Mac OS X.
Alan G
