You can create a link from one business process to another, or from a line item to a business process. Other users will be able to click on the link and view the referenced business process. Linked records are added and viewed from the Linked Records link at the bottom of the BP form. If records have been linked, the number of records will appear next to the Linked Records link.
Note: This option is available only in BPs that have been designed to accommodate linked records. A user's ability to view a linked BP record is based on the user's permissions. If users cannot see the record in the log, they cannot see it in the link.