Did you create a table to hold the data of who modifies the record?
Have you tried using a portal to list the last 10 people in this modify table?
To expand on that, don't use a repeating field for this. Instead define a table of related records and display them in a portal. Each time someone edits the record, just create a new record to log the relevant info in the related table. Your portal can be set to display 10 rows and if you sort the portal correctly, the 10 most recently created records will be listed in your portal.
Got it. Thanks for your help on this.