Use a company-level file for the proposed sponsorship and separate secure participant files for personal records and notices.
Keep access proportional to the role
A coordinator can track whether a requested item is outstanding without holding every sensitive document. Ask counsel for current instructions and a responsibility list. Record which employee each submission concerns so shared company materials do not obscure omissions, inconsistent names or unresolved personal information.
Expect the first review to produce a file structure and an access rule, both easier to establish before documents start arriving than afterwards. Keep a company-level file for the proposed sponsorship, the corporate authorisations and the general correspondence. Keep a separate secure file for each participant holding identity records, family information and any personal immigration notices.
A coordinator can track whether a requested item is outstanding without holding the item itself, and that is usually the right arrangement, since a colleague should not hold another employee personal immigration history simply to manage a schedule. Ask counsel for current instructions and a list of what each participant must supply personally, then send that list to each individual rather than through a manager. Preserve every notice received in the participant own file with its date.
Agree at the outset who may see each file and for how long it is retained.