It's not always easy to select the main row or column after adding a sub grid and adding content. Sometimes its impossible! Maybe a backwards Hereditary selector in the layout tab would be good

If you hover over the subgrid, a little gray tab will pop up that says 'Subgrid Column'. Click on that tab and a drop down list will appear. Click on 'Row'. Your main row is now selected.

Or go to the 'Inspector' tab. There you can find your row (or whatever else you need) easily. Hover until it is on the row you are looking for and then 'click'. Your row is now selected.

Thanks Michael, its a little finicky though because if you cross other elements it will change especially if the margins are small

Thanks Michael, I can see that even if I select a button element in a sub grid for example the drop down list will go all the way back to the main row/column, this is perfect. Cheers!

Yes, it's pretty sweet the way that works. Glad that was helpful James.