Try

/targetparty
/cast blessing of wisdom

Each successive press will target the next person in the party. You have to pace your presses making sure the global cooldown is up on the blessing otherwise you will skip a party member.

or

/cast [target=toonz,modifier:alt][target=toony,modifier:ctrl][target=toonx] blessing of wisdom

Hold down alt for toonz, ctrl for toony, otherwise toonx.