You don't need to.
In Panel1 panel there are 4 EditText views and their index begins with 0 and is incremented by one when adding the next one.
This means that
EditText5 = index 0
EditText6 = index 1
EditText7 = index 2
EditText8 = index 3
so no need for the Tag property.
But in the event routine, which is in the example the same for all EditText views, we need the Tag property to know what EditText view raised the event.
The advantage when you control the adding order is that with the index you directly know what view you are looking for, avoiding to go, in a loop, through all the views and check the Tag property to check the good one.
If you want to manage different sets of views, put each set on a seperate panel and then it's quite easy to manage them.