Accommodation and maintenance papers- spouse visa extension

[Gingiamano]

Hey everyone

I am just getting my application sorted (Spouse visa- further leave to remain- 30 months) in 10 years route. My visa will expire 7 Aug and I need some urgent guidance regarding the accommodation papers. hence I am posting some questions and hope to get helpful answers. Thank you.
When I first came here on spouse visa, we showed these accommodation papers
a)Land registry in my mother in law's name(her son, (my husband) lives there as extended family, hence so do i)
b)Letter from her stating she approves of our stay
c)Letter from surveyor stating the no of rooms in the house
d)sponsor's undertaking
there might be other documents, but I can't recall which ones

1. Hence, can I show the old surveyor's document, made in 2014.....or will I need a new one for extension?
2. Do we have to send original land registry papers ?
3. Do we need to show sponsor's undertaking again? if yes, could you please share the link of document download.

4. Any other documents I am missing.
Thank you so much for this forum.