Hyphens, En Dashes, Em Dashes

Q. Do I treat “as and when required” with a suspended hyphen when adjectival? E.g.: “an as- and when-required basis.” Or join up: “an as-and-when-required basis.” Unfortunately, we’re stuck with transcribing substantially verbatim legislative debates.

A. Ick. If you were able to reword this construction, you could simply write “when required.” But since you’re stuck, it’s probably better to quote the offending phrase than wrangle with hyphens: an “as and when required” basis.