iPhoto has never been designed as a shared network database. What you want to do is currently not supported, Jerry, sorry.
Some things to consider - assuming you are using the most recent iPhoto version:
- iPhoto '11 will not allow to have the library be opened by more than one user at a time. It will lock the iPhoto library, if it is already in use.
- The iPhoto library needs to be on a disk, that is formatted MacOS X Extended (Journaled), otherwise iPhoto will not open it. Most network volumes have a different formatting.
- Network access is considerably slower than the access to a locally connected drive. You will have a noticable decrease in performance when working over the network. Editing the images will be no joy, if each and every access to the databases inside the library needs a network access.
- Since iPhoto is not specified as a network database, there is no built-in protection against network drop-outs and transmission errors when doing database transactions. You will be risking to corrupt your iPhoto library.
Save sharing options would be:
- Let the iPhoto library be managed by one user, but give read-access to your family members using the "Sharing" preferences. You can share all albums or selected albums on your local network for browsing.
- Put your iPhoto library on a portable drive and let each family member use the drive in turn.
- Use shared Photo Streams to share your photos.
- This is Apple's recommendation on how to share a library:
iPhoto: Sharing libraries among multiple users
Another issue to consider is if the library is accessed wirelessly and a drop out occurs (which is not uncommon) while writing to the library's database or other files the library can be damaged. If you must have a central library follow leonieDF's warnings and use a wired LAN for your connections.