Hi Maxim, 

Thanks for your reply. All files are kept on a server, Which our Macs are connected to as a Drive. 

In terms of the location of the files, its by project>Drawing>Models>Blocks>Block Library>Bathrooms (then their saved here) While the plans for the rooms are similarly saved project>Drawing>Models>Building number>Apartment Number.

Does this mean that for relative paths we need to have the files on the Local Drive only? Then move them to the server i.e. external drive?

Thanks 

Tom