Add data from lastCell in Range

Hello Excel experts!

I am creating a program and I need help:

From the following image, I have a variable number of references and a range of values associated with it.
What I would like is to click my button (add or delete) and add or remove from the last row where there is a reference. It is important that it is not through adding rows...

The total of Reference is until row 12 (Yellows), and the forumla content of the created ranges for every reference must be as the green cells.

Captura de pantalla 2022-04-22 122200.png


Many Thanks!

Where do you get the reference letter? A, O, W, F, G, K, ... ?
& do you want to adjust the formatting so the last row with values is enclosed in a thick outside border?