You are not grasping this clearly. I will attempt
The Petitioner/ Sponsor ( your father) fills out an I-864 for EACH son/daughter. If dad is married , he counts as 2, if single he is 1. If dad sponsored someone other than wife, add one more to dad
the Petitioner/Sponsor ‘s I-864
A-Family 4 plus Petitioner Sponsor 1 , the total is 5 ( I sent you link see income needed)
B-Family 5 plus 1 , needs 6
C-Family 5 plus 1 needs 6
D-Family 4 plus 1 needs 5
The Joint Sponsor w $200 K income , starts out with 5 ( even though they are not LPR yet and petitions are pending, wife and children are counted as dependents. So
Joint Sponsor does an I-864 for each family
A-Family 4 plus Joint Sponsor 5 , needs 9
B-Family 5 plus Joint Sponsor 5, needs 10
C-Family 5 plus Joint Sponsor 5, needs 10
D-Family 4 plus Joint Sponsor 5, needs 9