This is indeed possible and has been successfully executed. However, for the time-sharing agreement between “A” and “C” to be valid, it must specify non-overlapping schedules. After your time-share proposal is approved, and the other applicants are subsequently dismissed, you’ll need to await the finalization of those dismissals.
When an MX (Mutually Exclusive) group includes both a 5-point applicant and a 4-point applicant, a point-based preference system is used to determine the tentative selectee within the group. Here’s how it typically works:
In 2019, the FCC revised LPFM rules to allow for discussions regarding time-sharing among members of mutually exclusive (MX) groups before the announcement of tentative selectees. (Refer to FCC Tech Order, paragraphs 35-44)