Power Form - How to pass information from Subform to Parent form when a row in subform is selected

Hi, I have a Power Browse form with a sub-form . The sub-form displays substitute items related to the item shown in the parent form. I’d like to perform some logic on the parent form when a row is selected in the sub-form and a button is clicked on the parent form.

Could someone guide me on how to pass the selected row data from the sub-form back to the parent form?