Price the list, not the fight
Guest-list negotiations go sideways because they happen in feelings. They go better in arithmetic: at $160/guest, every name is a price tag, and "we can host your twenty at $3,200 or upgrade the photography" is a sentence both sides can hold. The list is the budget — saying so kindly, early, is the whole technique.
The A/B system
The A list gets invitations the moment they print; the B list gets them as declines arrive. Unromantic, universally practiced, and invisible if executed with printed-stamp-ready B-list invites ready to go the day the first declines land. The system converts the awkward waiting period into a pipeline.
The parent conversation
Parents inviting friends is normal and deserves a structure: a defined allocation (10 names each side), priced transparently at the marginal cost, with the offer that their allocation can buy a nicer bar instead. Most parent-list conflicts are really information gaps — the per-guest math closes them faster than any compromise speech.