Macro to add defined text to the end of multiple defined columns of data

Hello everyone,

So seems as soon as you solve one issue another pops up, this is different to my previous solved issue so I have started a different thread, hopefully this is OK.

So I have a sheet that pulls data from another source, and enters it into columns. The amount of data can vary however the number and locations of the columns will always be a known factor. What I would like to do is have a macro that will run and add two lines of data at the end of each of a defined column in the first two blank cells. So for example:

A B D G
1 1 1 1
2 2 2 2
3   3

Magic button push!

A B D G
1 1 1 1
2 2 2 2
3 F 3 F  
F O F O
O   O

The data that needs to be entered at the end of each column is always going to be the same and so can be hard coded just like the columns of data that are always know.

Hopefully this make sense but please do ask if I need to clear anything up. Thank you in advance once again for anyone able to help.