Presumably you now have grant of probate.
Is there a reason that he is refusing to sign the form ?
The assent is the document which transfers the property to the beneficiaries .
As he is not a beneficiary of the house but you and your wife are, what is the release form that he is being asked to sign?
The executor doesn’t have to sign the will. An executor can witness the will but the beneficiary cannot and hence, if the beneficiary has witnessed the will (even though he is in executor) then any bequest to him is void.
If the will does not mention is that he gets 20% of the proceeds, then he doesn’t get 20% of the proceeds.
As I said earlier, the assent transfers the property to the beneficiaries which you say are you and your wife. You are then free deal with the property as you wish, live in it, sell it, rent it out, whatever you like.
It appears, that at the moment, the property has not been transferred by the assent and they are looking for instructions from the executor executor to market the property.
Are you able to attach a copy of the will?
I will clarify the sentence.
The property is transferred to beneficiaries by way of the assent.
Then the beneficiaries can do what they like with the property without the executor’s involvement.
That should be the situation that you are in.
What I don’t know, is why that hasn’t happened and it may be that the solicitors are going to market the property without transferring it to you and your wife and that would need the executors consent.