How to connect a Declaration of Trust to deeds

I have a declaration of trust with another person, after lending them money to enable them to purchase a house.  The deeds are in the other persons name.  How do I or we notify the Land Registry of the declaration of trust and attach it to the deeds of the house, so if the house is sold the money is returned to me?  

Abigail - please refer to our PGs 19 and 24 for guidance on how to protect third party interests and/or private trusts.
I would recommend seeking legal/finanical advice as well to ensure you both understand the legal position and how the law will apply re any sale/return of the monies owed for example