Synchronizing data between HR database, Active Directory and Sharepoint

Our company has 3 sources for employee information:

- Active Directory

- Deltek Costpoint

- Sharepoint User Profile fields

The employee information is not consistent across these three systems and we're trying to figure out the best solution that would allow us to enter employee information in just one place and for it to propagate to the other two systems.

The management believes that the "Official" employee information is the one in Deltek so it seems that the best way to have only one data entry solution would be for HR to enter the information in Deltek, for Deltek to export it to AD and then Sharepoint would import it from AD.  However, is that even possible?  Also, that would only take care of the employee information such as first, last name, phone number etc.  What about assigning employees to the appropriate security groups and email distribution lists?  It seems like this can only be done in AD.  I'm sure our situation is common for most other companies where there is a separate HR database, a Sharepoint user profile and Active Directory.  I would appreciate any suggestions/feedback for how to get these three systems to work, ideally with just one location where the information is entered to avoid duplicate work and inconsistencies. 

thanks