spells – Earliest access to 3 action Harm while sustaining Animate Dead

I seems to be a great combo to use 3 action Harm while you have an undead minion, to heal it while you harm your enemies. Unfortunately you need one of your actions to sustain Animate Dead.

Haste does not work, as the extra action cannot be used for sustain.
I found Effortless Concentration, unfortunately it is only available on level 16. Is there an earlier solution?