As the title suggests: is it possible to indent the second flow but not the first one? Do I need to do something clever with music frames to achieve this?
Well that was embarrassingly obvious! Thanks Lillie
One way would be to turn off the indent in Layout Options, then in the 2nd Flow add a hidden Coda at the beginning.
Although of course you can “add” an indent in a layout where the default is no indent, but you can’t go the other way; a system can only move to the left as far as the layout’s indent is set to.