I am trying to do some automation of cells and have an IF Function
started. As I continue to build this automation, I am wondering if a
VBA solution is better? Any help/suggestions would be appreciated.

Current function in all ColB cells starting at row B2 (B1 is empty on
purpose) is as follows:

=IF((A2)<"", CONCATENATE((A2), ".", "1"), CONCATENATE((A2), ".",
(RIGHT((B2), (SEARCH(".",(B2),1))-1))+1))

This produces the following

ColA ColB
1
1.1
1.2
1.3
2 1.4
2.1
2.2
2.3
3 2.4
3.1
3.2
3.3
4 3.4
4.1

Ideally, we want all cells that now contain 1.4, 2.4, 3.4, etc to be
blank as with cell (B1). We would like ColB to be locked so no one can
edit this column. It should also update automatically if someone enters
a value in ColA.

Any thoughts/suggestions would be greatly appreciated.

Tammy