We need to build a two-step Umbraco Forms workflow in Umbraco 10

Questions
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1

We need to build a two-step Umbraco Forms workflow in Umbraco 10.

Step 1 (Lookup step)

The user enters CustomerId and MeterId.

On submission of Step 1, we must validate and look up an existing Forms record using the composite key:

CustomerId + MeterId

If no matching record exists:

  • Show an error

  • Do not allow the user to proceed to Step 2

Step 2 (Prefilled + locked fields)

If a matching record is found, Step 2 should display:

  • Name (prefilled from the matched existing Forms record) → read-only / locked

  • Email (prefilled from the matched existing Forms record) → read-only / locked

  • Address → editable input (the user can modify it)

Important: The user must not be able to modify Name or Email. This must be enforced not only in the UI (read-only fields) but also server-side.

Step 1 is already implemented.
How should we prefill the fields when Step 2 is displayed?