Automatic insert a point after type in a cell that merged cell

Hello Bos ?? Can u help me please..
How I can Automatic insert a point after type in a cell that merged cell ?
Example :
when I type on cell B9 (merged cell), I type A33 and I want after enter the text, on cell B9 change become A.1.1.

Thank's before

Hello Mr. Stormseed, I have attached the Example.xls file. Thank's before for your help sir.