I'll add some meat to the bone:
So I have 3 SP Lists which share some details with each other, i.e; Purchase Order, Customer, and Product.
I'm creating an app where the first screen, form with one SP List captures this information with some other details.
Without submitting or saving this form but simply navigating to the next screen with a new form and the 2nd SP List, I wish the values of the Purchase Order, Customer, and Product values from the first form to be copied into the relevant fields of the 2nd form.
Only at the end I will submit and save, adding all data to the respective lists.
Hopefully this helps further.
Thanks