Why is not possible to create a custom scenario and still use the build-in distribution modes?

Currently, if you only want to change one aspect of the map you have to recreate it ALL from scratch - starting positions for all player, number of armies, manual wastelands etc. - troublesome work on bigger maps.

Want I wanted to do is create a scenario, where an AI starts in a specific position, while the rest of the player could chose their starting spots, which turns out is impossible.

I understand that, for example, creating manual wastelands could mess up with modes like "random warlords", but I don't see other issues.



Another idea, just in general, is the option to select multiple territories at once, when creating custom scenario, because currently you can only change them one by one.