(1) If the difference between the existing total monthly support order and the proposed support obligation is less than 15%, the change may be considered negligible and the child support provisions of the existing support order need not be modified.

(2) Provisions in the existing order for the medical needs of the child may be modified even if the change in the child support amount is negligible. Where an existing support order does not contain a provision for the medical needs of the child, the order may be modified to include a medical support order even if the change in the child support amount is negligible.