Writing a data under a specific column header

Good day,

Is there any way available that allows the data to be written under a specific column header of our choice?

To put preciosuly, we have data already present under the headers say Col1, Col2, and Col3 and I need to insert the data under Col4 alone. I identified this can not be achieved using the normal file writer snap as generally it supports overwrite as an option. Any methods to merge the data into a single sheet?