Merging Cells in a Repeating Group

Hi All

I’ve create a dashboard template where I can change the layout on the fly (by selecting the rows and columns), add widgets into the cells and drag and drop those widgets into other cells. Here’s an example of two widgets in this dashboard with the layout option menu open:

Which is fine but what I really want to do is to be able to stretch widgets over cells, so something like this mockup:

The closest I can get is being able to add a cell to the widgets ‘additional cells’ field and then searching for widgets that are in current index merging with widgets where their additional cells field contains the current cell. I’m then able to get this:

I have a feeling this might be a stretch too far for the repeating group functionality but if anyone knows of a way, I’d be much appreciated!

Thanks
Stew