Death of a Tenant in Common of Unregistered Property

Hi
I've read through this forum and the on line links,  but can't see an answer for this scenario.
My father has recently died.
The property was bought in 1965, is not registered and dad owned it jointly with my mum as tenants in common.
My mum, me and my sister are trustees of Dad's will. His share of the property is left to the trustees to be held in trust for my mum for the rest of her life, and after my mum's death to me and my sister.
We would like to register the property, but are unsure as to how the owners should show on the land registry, and exactly what forms are required.
I understand an FR1 and DL, but should there also be  a Form A ?
Would it be correct to register in joint names of my mum and ''The Trustees of (my dad), deceased'' ( no individual names of the trustees, as me and my sister are not wanting to be registered as owners)
Or the joint names of mum and dad as its first registration and ive read that a death doesn't actually need to be registered ? 
Any assistance would be greatly appreciated. 
Many thanks
 

Hi Alison - you need to decide how you want the legal ownership to be registered and IF that is changing, so for example Mum is transferring to new owners, then that will trigger the need to register for the first time.
Forms FR1 and DL are correct but the form A you refer to is not a paper form but a form of restriction often applied for to show how the property is held in trust
If you don't want to be registered as joint owners then please do seek legal/financial advice to decide what's best. For example you may decide to do nothing at this stage as the ownership, will/trust created etc are already protected and you are all aware.
The legal ownership has passed to Mum as the sole surviving joint owner so unless that changes there is no compulsion to register.
There's no online guidance for your scenario as the property is unregistered and we would not be involved unless the legal ownership were to be changed