Merge cell table widget heading SAP Analytics Cloud Story

Using SAC Stories, Live connection via APOS.

I have a requirement where for notification types we see across Plants the monthly and YTD count.

Basically First column is Dimension Notification Type and Then we have Plants dimension across on top and within each plant there is MonthCount and YTD.

What we are getting is 'Plant1' heading in one cell and a blank cell on the right , above the YTD. I can't seem to merge the cells to have one cell above 'Plant1' under which we have Monthly and YTD columns.

Any options?

Cleo