Per Set O Form, page 40, Secton 11A box 7 wrote:If you have a spouse or civil partner listed in section 2 of this application form who is applying at the same
time as you, please provide documentary evidence of cohabitation since you were last granted leave (up to a
maximum of two years). Evidence provided should cover the whole period and be in the form of official letters
or documents, addressed to yourself and your spouse.
Per Immigration Rule 196D (as relevant to you) wrote:
196D. The requirements to be met by a person seeking indefinite leave to remain in the United Kingdom as the spouse or civil partner of a person who has or has had leave to enter or remain in the United Kingdom under paragraphs 128-193 applies to you (but not paragraphs 135I-135K) are that the applicant:
(i) is married to (condition met) or civil partner of a person who has limited leave to enter or remain in the United Kingdom under paragraphs 128-193 (your current WP visa) (but not paragraphs 135I-135K) and who is being granted indefinite leave to remain at the same time (you as the primary applicant, and wife as dependent); or
(ii) applies if you already have ILR; and
(iii) meets the requirements of paragraph 194(ii) - (v) Relates to your spouse being granted dependent visa, by default all conditions met; and
(iv) relates to LIUK; and
(v) was admitted with a valid United Kingdom entry clearance for entry in this capacity; and
(vi) Refers to convictions
(vii) Refers to 28 days overstay allowance
Putting the two together there is no explicit requirement for 2 year cohabitations, and no requirement to show 'jointly named' documents.
You may wish to carry a copy of these rules just in case.
Good luck.[/quote]