JJinLondon

The roofs are being done manually.   The roof edge exactly meets the siding on the upper roof.  If I imbed it at all, it will render with the siding stripped off.  If I pull it away the spike if wall from the lower wall only gets bigger.
I suspect this is an issue because the garage is sunken.

I'm sure someone has resolved this but I have searched the forums and must just be using the wrong key words to catch it.

Any help would be appreciated

RESOLVED.

When I tried dragging down the height of the wall it took down the height of the ceiling affecting other walls.

But I did 'solve' it.

note the existing ceiling height.

Define a ceiling pane only over the wall you wish to lower.  

Set the slope to 1/16 and lock it. (That was the lowest i was permitted)  Lock the slope and enter the desired absolute height.

So far you get a hole in the original ceiling, a lowered wall with an ugly section of ceiling above it.

First fix the hole:

Copy your ceiling pane and paste it in place.   Choose one of them and set the ceiling height to that of the original.  That plugs the hole.

In a floor view, select the ugly ceiling pane over your lowered partition.  Choose material and select insulation- air gap.

The smaller the section the better as the ceiling does not perfectly get patched because of the slight slope.