Can I add a co-applicant partway through the process?
It depends on the workflow — in most cases it’s cleanest to add all co-applicants when you submit, since screening and review are typically tied to the full applicant group.
From the guide Rental Applications.
For applicants
Submit your information, income and employment details, and consent to screening in one place, then track the status. Provide accurate, complete information — it’s your own, and it speeds up decisions.
Read the whole guide: Rental Applications