Splitting Title

We built a new house in the garden of our existing house in 2018. The two plots are fully separated with walls and fences and having separate entries.

The "OLD" house has tenants and we moved into the new house.

The current title covers the land that contains both houses and there is a mortgage charge on the entire plot. We plan to clear the mortage as part of the sale process.

We are planning to sell the new house next year and to move back into the old house. This will involved splitting the title.

Questions:

* Is there any need to get this split done in advance of any sale or can this be done at the time of the sale as part of the normal conveyancing process?

* Will this add additional delays to the conveyancing process?

Thanks in advance

David

David - I've answered your other identical post.
The forum is public but very rarely does anyone other than ourselves at HMLR respond. We use the forum to answer general enquiries and to offer answers to frequently asked Qs. 
Duplicating posts won't trigger wider comments. Just extra typing for you and I