Optionally Create New Contact when creating New Relationship
This has been beneficial for our firm, and I thought it might want to be considered as default functionality at some point.
We added a screen at the beginning of this flow that allows the user to first specify if they want to choose an existing contact, or create a new one. If they want to create a new one, there's a screen that allows them to add it.
New contact is set as the default value for the Contact field on the last screen