How can I fill a form with values read from a different form

I have a process with two manual steps.
On the first step a customer enters a large number of values into components.
After submitting the form the next step is assigned to a backoffice employee, who evaluates the values - but who can also make some corrections (this is the second manual task in the process).

How should I read the values from the first step and put them as component values on the second form?
I have approximately 200 values on each form and they can have the same MIDs on both form templates.

And I don’t want to store them in process variable(s).

One of possible solutions is to add a service task to the process before the second manual step that will call the handler to the system where your forms are stored, e. g. formstore. In the handler you can define the values that ​​you are interested in.