You can create relationships between existing Records by adding a 'link' between the Records.
The example below creates a relationship between a Stakeholder and Event Record, but the same steps can be completed between other Entity Types (eg. An Action Record linked to a Stakeholder Record, or a Document Record being related to a Property Record)
1. Run a search for the Stakeholder and open the Record
2. On the right-hand side of the Stakeholder Record is where all the related Records are shown. To edit related Event Records, select the [+] icon on the Event Ribbon
3. At the top of the page there are 4x Tab options, stay in the [ Assign ] Tab.
4. Run your Search to find the Event that you want to link to the Stakeholder.
5. For one single Event Record, click the quick link chain Icon which will create the relationship
6. You will know that the relationship has been successfully created when you see the "Success" pop-up message.
The Event Record details will also disappear from view. This is because it cannot be added a 2nd time to the same Stakeholder Record.
If you want to know how to add multiple existing Stakeholder Records to one Event Record, have a look at this support article