Yes you need to do an assent. If its Land Registry you could probably pick out the relevant Form from the Land Registry rules and lodge it in the Land Registry. If its Registry of Deeds, again its an Assent in the usual form.
The problem is I suspect that without checking the situation, the parties, the beneficiaries etc.,etc no-one on this board can tell you that what you intend to do will achieve the ultimate aim - to vest the property in the person entitled so that the title is saleable in the future. I regularly come across d.i.y. situations that fail to take cognisance of problems that would immediately be apparent to a solicitor.
I would suggest legal advice should be taken.
mf