Aloha Jamie,
Mahalo for asking a good question. You are right that counseling is going to take some time. Iʻm glad to hear the father is going to get counseling for this keiki. It sounds like the keiki has experienced a lot of changes recently. Moving in and of itself can be challenging for anyone, especially young keiki.
Iʻd suggest trying to provide as much structure, routine and consistency as possible and suggesting that the father and child care providers do the same. Predictability and consistency in schedules and routines are important at a young age and when other changes are occurring.
Work on helping the keiki build emotional literacy and understanding. Try to help him recognize what is making him angry and try to catch the earliest signs of anger presenting. Try to help establish safety for the keiki and remind him that he is safe. This can be done through finding calming items that can help him such as stuffed animal, stress ball, sensory items, etc. I like to use a safe place script by Conscious Discipline that states "this is a safe place and I wonʻt let anyone hurt you so I canʻt let you hurt anyone else because this is a safe place."
When keiki is calm try to process what occurred at an age appropriate level and help him identify better choices for next time. Also, practice the choice that he can make next time as this will help to rewire his brain into making more pono choices in the future.
Hope this helps! Mahalo!
Shannon