If the contact is the Currently logged in user you could use a Metadata record on the Step in question (use the Portal/Power Pages Management app to configure metadata records).
If the contact is not the currently logged in user and you are creating it on a previous step then.....
I'll explain how to set it up, but the prefill may not work (maybe a bug at the moment).
- Use the Portal/Power Pages Management app
- Open your Multistep form definition and then open the Step in question
- click the "Associated Table Reference Tab"
- set Table Reference On Save to Yes
- for Table select contact
- for Relationship Name select account_primary_contact
At this point you hit the first bug, if the dropdown for "Target Lookup Attribute Logical Name" is disabled then you will need to populate the rest of the mandatory fields, save, and then refresh the page to enable the dropdown.
When the "Target Lookup Attribute Logical Name" is enabled select Primary Contact
Other fields to be populated
- Tick the box for "Populate Lookup Field" - this checkbox is what should prepopulate the field on the Step
- for Source Type select Previous Step
- for Reference Entity Step chose the Step where you defined the Contact record
That should be setup that is required, however when I tried it just now it is not pre-populating the field on the Step, but it is populating it as part of the save - so at the moment there may be a bug with the pre-population in the multistep.
