Attach Multiple Contacts to a Custom Record

 To attach multiple contacts to a custom record, perform the following steps:

     1. Navigate to Customization > Lists, Records, & Fields > Record Types. 
     2. Edit the custom record.     
     3. Click the Subtabs tab.     
     4. In the Title field, enter Contacts.     
     5. Click Add.     
     6. Click Save.     
     7. In the Fields tab, click New Field.     
     8. In the New custom field window, set the following:

• Label: Provide a Label (e.g. Contacts)
• Type: Multiple Select
• List/Record: Contact
• Store Value: Yes
• Optional: to show custom record in the Contact record, check Record is Parent
• In the Display tab, select Contacts in the Subtab field

     9. Click Save.