(1) Subsequent child is a parent's natural or adopted child, not the subject of the order being modified who:

(a) is not the subject of a support order and was born after entry of the support order being modified; or

(b) is the subject of another support order entered after entry of the support order being modified.

(2) Any other child must be considered in accordance with ARM 37.62.110(1) (b) .

(3) In a proceeding to modify an existing order, the support obligation of each parent is calculated considering all children, prior and subsequent, of each parent. Then the support obligation of each parent is calculated considering no subsequent children of either parent.

(a) If both calculations result in a decrease in the transfer payment due and payable from the obligated parent, the lesser of the decreases in the transfer payment is granted.

(b) If both calculations result in an increase in the transfer payment due and payable from the obligated parent, the lesser of the increases in the transfer payment is granted.

(c) If the first calculation results in a decrease and the second calculation results in an increase, or if the reverse is true, no modification is granted.