It seems the drafter of the variation erred in designating the family members as “executors” rather than “trustees”. As you cannot appoint an executor by deed of variation, I suggest their purported appointment is void, so that it is only the bank that is the executor and trustee.
In looking at the next step, I believe the first question is whether there has been any distribution to the original beneficiary.
If there has been no distribution, then as Simon has said, upon receipt of a copy of the deed, the executors are on notice of the gift into trust. However, have they been instructed to give effect to that gift? If not, can they safely assume that instruction as the beneficiary might already have set monies aside to satisfy the gift.
A similar question arises if a sufficient distribution has been made, as the beneficiary might intend those monies be impressed with the trust. If the monies are already held by the beneficiary, I believe that the trustee will be the beneficiary, as the person holding the trust assets when the trust was declared, and not the bank.
In the absence of anything in the deed about whether the trust is imposed on assets in the original beneficiary’s hands, prima facie it is the entitlement in the executor’s hands that needs to be considered. In this case, in the absence of any thing to the contrary, I believe the bank will be the trustee.
If it is intended that the trustees be the family members, the bank will need to appoint them (although it might be worthwhile approaching Chancery counsel to make sure that such action does not just exacerbate the problem).