Howdy @Stefanie Welcome to the 
Make Community!
IML Nesting:
You should be able to Nest replace functions (and all make IML for that matter) in a similar style as you would nest an excel formula.
Unfolded to make it easier to read
For readability purposes only DO NOT:
Write it out with the spaces/tabs like this in make(causes problems/mostlydoesn’t save)
Feature Request Quick(self) Note:
Make the IML editor more tab/spaces friendly, and also multi cursor editing capabilities. like vs code.This would be a huge game-changer for readable complex IML.
Tabbing currently does not work at all. as it tabs you out of the edit pane.
Hope This helps!