Tenants in Common to Trust and remaining tenant after a death

I have not been able to find a definitive answer with example.  My parents were tenants in common and dad has died.  Probate has been gained and his will was that half the house is put in a Trust, which has been set up.  

We need to amend the land registry to show XX Will Trust and Mother.  Which forms do we need as it isnt clear and do we pay in full or half house value given mum is already registered as a tenant in common on the LR?

Thanks

Lyndsey - we register the legal ownership so if that is to be changed then we would need an application by which your Mother transfers the legal ownership to herself + whoever.
 

Thank you Adam, we may be ok with this now!

Lyndsey - hope so. The key from our end is that we are not involved in the will/decisions made. We deal with the outcome and I always advise people to seek legal/financial advice before deciding what's 'best' and once decided the forms/guidance etc is there to fit that need

Very true Adam.  We are trying to navigate as a family as we have been quoted extortionate fees to make the change by a solicitor.