Add the option in Approval Reports or Review for each individual entry to be approved, possibly by different managers.
Example: Empoyee works Monday morning for Manager A, and Monday afternoon for Manager B on different job sites. Manager A has the option to approve only the entries that they supervised and then Manager B can go in and approve his jobs.
Jorge Dardon commented
Exactly....and manager A could be a customer that should only be able to see the job codes that pertain his/her project. Manager A should not be able to see anything related to manager B's project.