Robby, I wonder if it would be too cryptic/cold/Vulcan to swap the Arranger field for three “Contributor” fields; that way, you can enter their info as needed, then insert tokens to best reflect their contributions, e.g.:
{@ProjectComposer@}
{@ProjectContributor1@}
{@FlowContributor1@}
becomes
Modest Mussorgsky
orch. Robby Poole
ed. Tony Ward
(I would not presume to edit your work, BTW) =)