First Registration on death of one of the Tenants in common

My mother and father bought  a house in the 1970's this property has never been registered. They then bought a garage and drive in the 90's  this part  was registered at the time of purchase. Both parents held the house and garage as tenants in common. My mother recently died and her share of the property has passed to my father under a Will trust which stipluates that  her share of the house and garage go to  my dad. Myself and my sister as executors have had to put it into a Trust whereby on his death it then must come to us.
1.Do I  now have to by law apply for First registration of the house?ie would this be classed as a compulsory registration attracting the higher fee of £330.
2. if so would the house be registered just in his name or with myself and sister as eventual owners under Trust
3. Do i have to also advise HMLR that the garage and drive are now in his sole name and do i register it in his sole name or also name myself and my sister as beneficialries on his death as there is a Trust which stipulates this?

Any help much appreciated. i don't wantto have to do any more paperwork than necessary!

Steph - sorry to read of your loss.
The legal ownership of the registered and unregistered garage/property passes to Dad following her death. 
The TIC, wills and trust created relate to their beneficial ownerships
1. No as the legal ownership has not been transferred. 
2. If a voluntary application was submitted it would be in his name. You don't register what might happen next.
3. You don't have to advise us that the garage and drive are now in his sole name. The death is sadly factual so can be proven as and when the actual legal ownership is transferred in the future
But you can update the register - HMLR Guide Page  · HM Land Registry