(d) where it appears to the Commissioner that an agreement as to the payment of a lump sum whether by way of redemption of a half- monthly payment or otherwise, or an agreement as to the amount of compensation payable 1[ to a woman or a person under a legal disability] 4[ ought not to be registered by reason of the inade- quacy of the sum or amount, or by reason of the agreem agreement having been obtained by fraud or undue influence or other improper means, he may refuse to record the memorandum of the agreement 5[ and may make such order] including an order as to any sum already paid under the agreement, as he thinks just in the circumstances.