@aspirant0508 it's up to you kung saan mo gusto ipa-certify yung documents mo, as long as valid siya and acceptable to immigration. Affidavit of cohabitation? Or do you mean affidavit of sponsorship?
Have you checked the Document Checklist? If the checklist indicates that you need financials (even the school doesn't request for it), you have to include the financials. If it's not on the list, you're good to go.