Help with an IF (I think) statement please

Hello, I was hoping someone could help me please. 

I have a column called ID . Then there is a column (Column 1) with names that have three letters in front of them then a dash before the name starts.

Then there is a column with just names (Column 2)

I have merged these 2 columns together now called Column 3.

I need the ID column to show the ID of both these columns, but at the moment its only showing the one with just names (Column2)

Is there something I can write in Power Query or as a calculated table in data view that says something like, if Column 3 shows names then show this in ID column, and if column 3 shows names with three letters in front, then show that one in the ID column?

I hope that makes sense?

Thank you for any help