Maybe go with:

#show Rejuvenation
/castsequence [Target=D] ,,,,,,,,,Rejuvenation
/castsequence [Target=C] ,,,,,,Rejuvenation,,,
/castsequence [Target=B] ,,,Rejuvenation,,,,,,
/castsequence [Target=A] Rejuvenation,,,,,,,,,


/assist [Target=A]
/cast [help][help,Target=TargetTarget][help,Target=TargetTargetTarget] Regrowth