How do I count multiples in a list and display only unique records in output

I’m building a shorter list from a master list using a dropdown component. I want to count the multiples and display the record with its count value. I can’t figure out where to add the logic for this.

I need to be able to count the multiples as each item is selected in the dropdown and attach the value to that item, so that the next time that item is selected it will increment the attached count.

For example, the street address is 1000 Elm Street and the count of multiples is 3:
(the list should look like this)
1000 Elm Street 3
1010 Elm Street 1
1050 Elm Street 1
1160 Elm Street 2


I found a way to get the results I was looking for, I used the update record data function with the update via the formula function. Then reran the get record collection data function when there is a change in one of the page variables.