Hi Vince

I understand what you are asking.

Most often for AABA songs, on the final repeat of the form after solos, the ensemble will play the main melody (head) over the final AA and the singer will come in for the BA to coda (if there's a "ending")

That being the case there's no need for a DS or any specific chart instruction.

At the top of the B section you could add text "vocals start here final time" for musician info but it’s not necessary.

If there's a specific song you would like to arrange (for example) IN AABA x6 BA Coda. For assistance, please post your chart here, specify the arrangement desired (using rehearsal marks as above).

)BOB