Formatting column headers (Merge top, separate bottom)

Hi guys!

I've started using PowerBI to visualise and summarise work data and it's been an amazing journey so far.

I am currently stuck on a bit of formatting that i thought would be simple but turns out not quit.

So I have compiled (through just normal sum values and some DAX functions) a table like this one in Pic 1.

Not sure if it makes a difference but Area / Volume, Log Sales Total, (any of the Totals) are from summing values from the original tables.

the $/t or $/ha are from DAX calculations.

I am hoping to be able to merge the headers so it is more like Pic 2.

I've been searching through the internet but haven't come across anything that seems to help.

Anyone got any ideas?

Cheers!