For the egress composition, the lunar disc was completely blown out, 100% white with no alignment features.
So, for the composition, I had to match the profile of the lunar limb on the correctly exposed Saturn image with that of the correctly exposed lunar image, by "blinking" the 2 frames and adjusting their overlap.
This morning I had an idea to do the same with a screen capture from The Sky X Pro, just to double check that my positioning was accurate.
Here is the animation of a Sky X Pro screen capture and my composite showing a very good correlation.
Pity I did not record any BG stars like The SKy Pro X.
Cheers
Dennis