Urgent advice needed for suppose information in ILR LR form

[Cool Guy345]

Hi All
One of my friend is applying for ILR LR 10 year route and married, when the spouse details is given it in online form it automatically asks about additional documents
1. Evidence to prove your relationship : correspondence addressed to you jointly or in individual name at the same address to cover the last two years.
My question is :
does it have to be for the whole two year period or just recent any correspondence letter in the same address.
How can you submit this proof and what other documents can be provided to prove it?
Seniors plz advice specially zimba ,CR001,aman90 many thanks

[zimba]

indefinite-leave-to-remain/set-lr-appli ... l#p1858365

[Cool Guy345]

Many thanks zimba for your quick response much appreciated