Connecting Caldera Forms without submitting

Hello,
I need to embed the results of two caldera forms in a third one, but on the same page.

The first idea was to create a single form with a column for the income of a person and a column for the outcome. The result should then be displayed at the bottom. Everything worked fine.

But for the sake of responsiveness I had to cut the form in three different forms. One for the income, one for the outcome and the third to display the money which is left, calculating with the results of the other two forms.

I followed instructions of your article ‘Connecting Two Caldera Forms Using Passback Variables’

The first form contains the variable called {sum_income}, the second one {sum_outcome}
I created a redirect processor in both forms but I am not sure which url to take here.
I took the url from the code where it says
data-recquest="https://www.domainname.com/cf-api/CF58a44ca700887"
which is the url of the third form where the result should be displayed.

In the third form I created two hidden fields with the values {get:sum_income},{get:sum_outcome}. Then i calculated, using
%income%-%outcome%
which are the proper field slugs.

This is resulting in the two forms working just fine, but the third form is only displaying 0.

Am I doing something wrong? What can I do to fix this issue?

Thank you for your help