If the two sponsors have different areas of expertise, e.g. the Co-Sponsor works at a hospital while the Sponsor is MIT faculty, they should both be included. However, unless there is a clear addition to the field of expertise, these should generally be limited to the Sponsor. (Note; if the co-Sponsor is from another institution, they will need to go to IS&T to get a Kerberos account and MIT certificate in order to complete the proposal Certification and COI disclosure & Training)
If we are the sub on an NIH prime award and our PI determined some people are Key Persons, but the prime awardee does not include them, do we need to name them as Key Persons, have them complete Key Person certification and submit a proposal disclosure (if needed based on certification answers)?
Yes. If the MIT PI identified them as Key Persons for the MIT portion of the project, they should be included in the Key Persons on the proposal and the regulations/requirements apply.