Final answer:
The board of directors should ensure that the costs of amending the plan are not charged to the fund and that it does not competitively disadvantage the bank.
Step-by-step explanation:
Before granting approval for the amendment to the common trust fund language, the board of directors should ensure that the cost of amending the plan is not charged to the fund. This is to prevent the depletion of the trust assets and maintain the fiduciary responsibility owed to the clients. Additionally, the board should verify that the amendment does not position the bank competitively disadvantageously nor incur needless costs for the bank that could have been avoided.