The synchronization tool will not sync content in a family sharing plan unless that content is in the iTunes library on the computer's hard drive. You can use family share, but one users will need to download the all content from the family sharing plan onto the hard drive. Reference the following link on how to download content from other family members: http://support.apple.com/en-us/HT201085 If any of the synced content has DRM the user that has downloaded all the content and synced it will need to add their iTunes credentials to the MMS (in the config page, under the Content tab, in the iTunes box). Once you have completed these steps, use the following link to set up your sync tool: http://www.autonomic-controls.com/kb/index.php?View=entry&EntryID=136.
To determine if there is any DRM protected content in iTunes:
Open iTunes.
Go to the Songs view under My Music.
Right click or control-click on the columns.
Add the Kind column.
If any track has a Kind of 'Protected AAC audio file' you will need to authorize the server to play DRM content.