An institution may submit multiple post-submission items as long as they are allowed under NIH Policy NOT-OD-19-083.
Each item (including explanations and letters) is limited to 1 page unless a specific form or format page is required. For example, if a research team lost a senior/key team member after the application was submitted, and the PD/PI wanted to replace that individual with two substitute personnel, they could submit a one-page explanation regarding the personnel change, a 5-page biographical sketch for each new person, and a revised budget form. If the PD/PI also received news of an article accepted for publication since the submission, they could submit an additional one-page document stating the title of the article, list of authors with their institutional affiliations, and the journal or citation (if available).
Post-submission materials must be received by the NIH Scientific Review Officer (SRO) no later than 30 calendar days prior to the peer review meeting, unless specified otherwise in the Funding Opportunity Announcement.