Presumably the question was actually "when" will you know schedules (and fares) for next March. The answer is nobody here can tell you exactly when, although late this fall is likely.
Southwest group reservations are billed to each individual flier, so a single (or more) no-show is billed/refunded (to a voucher or whatever) per-flyer with zero impact on the rest of you. Southwest will @
Email you (or your wife) a form/spreadsheet into which you add the name, pedigree and payment information for each flyer. It's simple (well not as simple as telling your wife to tell these people to DIY, but it's not complicated).
These people can answer the rest of your questions:
https://www.southwest.com/html/air/b...up-travel.html