Groups are PITAs if not strongly managed.
That's why my group rules are:
1 person must be responsible for entire group and must pay a separate deposit in addition to a credit card guarantee for all room charges
that person must submit name of all guests and room assignments at least 30 days before event
guests may pay separately at check-in, but the responsible party still retains responsibility for any losses/damages/additional charges/no-shows/payment due because some of their group stayed only 1 night
If guests call before their name has been submitted as part of group and with room assignment, they're referred right back to the responsible party. If that person wants to pay for that guest's empty room for 1 night, that's their decision. They're paying for it, after all.
Once all guest names and room assignments have been received and approved, they each receive an email which includes policies, directions, instructions regarding potential late arrivals, and general group rules..
We did this. The person responsible held the rooms with their cc. When their 'time limit' ran out, we released all the rooms back into service. NOW, the folks are booking separately, altho we are holding them to the original specs in the group booking contract.
This is our second group of the year. The first group was 'We want it, here's our money, see you soon.' This next group tho, oy.
.