There is no relative addressing in Access, but I believe you are referring
to using a UNC path (i.e., \\SERVER\SHARENAME\filename.ext) to the data
file/BE vs a mapped network drive.  In order for this to be user friendly,
you need to provide some method for them to locate the data file...and then
relink the tables.  Using the linked table manager in Access is an option,
if all users have retail version of Access.  However, it is slower and not
as intuitive as other methods available.  The following link suggests a
method, but it too could use some improvement in respect to speed.

http://www.mvps.org/access/tables/tbl0009.htm

Speed in this example would be improved greatly if you open a recordset on
the first table you successfully relink.

To Link a new table:
File --> Get External Data --> Link

If the table links exited, but the location has changed:

Tools --> Database Utilities --> Linked Table Manager
Check "Always Prompt for New Location" (Lower left on dialog box)
Check the tables you want to re link.  

In either case, you will get a common dialog box.  Do not just point and
click to the back end database where the tables are, enter the address here.
NOT f:\someserver\somefolder\xyz.mdb
BUT \\MainServer\someserver\somefolder\xyz.mdb
Now, the tricky part.  If you have multiple tables to link, once you have
entered the path and file name, highlight and copy it.  Unfortunately,  you
are going to be promted for the path and file for every table.  In my case,
there are about 75 tables, so you can see this beats typing the same (in my
case very long) path and file each time.

The reason for using this is that not everyone using a sever has the same
drive letter mapped to it; however they will all use the same "relative"
address.