I agree sort of. Truffle is correct but there's an assumption I want to clarify. You must collect Demographic Information at the time of application. If only one person is present, you collect (or attempt to) on that person. The applicant that is present can complete the info for the non-present applicant. If they don't, you shouldn't try to collect on that person later. You would indicate the other applicant was not present.
For example, if I came in to your office and you collected my demographic information, I could fill out the co-applicant's info too. If I didn't complete the info on the co-applicant, you shouldn't leave it "open" and complete it later. Here's the instructions from Appendix B.
A co-applicant may provide an absent co-applicantâ€™s ethnicity, race, and sex on behalf of the absent co-applicant. If the information is not provided for an absent co-applicant, you must report â€˜â€˜information not provided by applicant in mail, internet, or telephone applicationâ€™â€™ for the absent co- applicant. [Appendix B to Â§1003 #5]
Now, it could be that I'm in person and the co-applicant is on the phone, but that seems unusual.