Bar number change question

I am trying to insert a bar number change, and couldn’t find information…

I have a flow that starts with a pick up measure. The part I am copying has the following order:

Pickup bar, 1, 1a, 1b, 1c, 2, 3, 4, 5, etc.

I am selecting on the second full bar (numbered 2 at the moment), and I select the note that starts the measures, I right click and come down to bar number change. I believe I create a change that should show bar 1a, but nothing happens. Further playing around I get 0a, 0b, 0c (since the pickup bar is 0). But no matter what I do, I do not get what I am trying to do. Does anybody have any suggestions or knowledge of this?