If you weren't using a cross tab, you could have a formula something like this:

StringVar creds;
if OnFirstRecord or {MyTable.staffid} = previous({MyTable.staffid}) then
creds := ""
else
creds := creds + ", ";
creds := creds + {MyTable.Credentials};
""

Put the formulain a details section to accumulate the credentials into a single string. To show the credentials, you would then have another formula like this:

StringVar creds;
creds

Put this in the group footer section of a staff member to show the credentials.

However, this won't work in a cross-tab. The only way I can think of to get this to work in a cross-tab would be to create a stored function in the database so that you pass the staff ID to the function and it will create the string using the same logic as the first formula above. Call this formula in a SQL Expression in your report so you can use it in the cross-tab.

-Dell