@VictorV Iām not 100% sure if this works, but you could try to make the partitions the relative percentage of size as to what you want and then capture as Resizable type image.
If Iām not mistaken, it will try to resize those partitions according to their relative size.
So if for example you have š as 20GB of a 100GB disk and š§ as 80GB of a 100GB disk, then it should come out as roughly 100GB for š on a 500GB disk and 400GB for š§
Alternatively and perhaps more flexibly, you could make a non-Resizable image with just the š partition and then include a SetupComplete script that automatically creates the new partition for you using diskpart.
Or, if you are more comfortable/knowledgeable in Linux, you could also try to do the same as the above, but using FOG postdownloadscripts (scripts that run after deploying the image, but before reboot)