I store Title separately from Subtitle, but in my main library view I display both using a composite column, separating them with a colon if the subtitle is set:
{title}{#subtitle:|: |}
However, when sorting by this field, The Memory Librarian gets sorted next to other “The” titles, not next to titles starting with “Mem”.
For my purposes, it would be nice to have another option in the custom column settings for the “Sort/search column by” drop-down. Maybe “custom” and the ability to provide my own template. Then I could use something like
{title_sort}{#subtitle:|: |} to have this field behave very similarly to the built-in title field.
Maybe I'm doing something silly and there's a better way to achieve what I'm after – I welcome suggestions.

Thank you for reading!