On the GDPR point, you can very happily keep a copy of the Will once released. On the basis that a beneficiary may one day sue your firm, you are entitled to keep the information you would need to defend yourself ( GDPR art 6(1)(f) ).
I spoke to ethics on a similar point once (not mutual Wills, but whether we could release estate funds to an executor in circumstances where we had a good reason to think he was going to defraud a beneficiary). On the basis that the estate funds were our clients legal property, ethics said we had no right to deny him receipt of them and we would not be an accessory to any later fraud. However it was suggested that we make E sign a duplicate letter of advice, confirming that we had advised him as to the the correct distribution of the estate. Applying the same principle, if H is a sole executor, W’s Will is his legal property but you could ask him to confirm in writing that he has received advice from you as to what he can and can’t do.
Releasing to the probate registry would be another good work around.
Alex Stanier
Allan Janes LLP