Make a LuckPerms event rank expire while preserving other ranks

An event rank can coexist with a player’s usual groups. Add it temporarily so the end of the event removes its benefits without replacing the player’s permanent memberships.
Follow the procedure
Choose an existing event group with only the required event permissions. Inspect its parents to ensure it does not inherit general staff or administrative access.
Run 
/lp user PLAYER parent info and save the current parent list. This gives you a precise comparison after the trial.
Use 
/lp user PLAYER parent addtemp event 5m on a consenting test account. Do not use parent set, which can replace other memberships.
Inspect the user’s groups and test an event-only action. Also test a normal rank feature such as an existing home allowance to detect unintended inheritance changes.
After expiry, verify that the event group has gone while the original parent list remains. Rejoin if the affected plugin caches rank-dependent state.
Apply the approved real duration only after the trial. Keep an explicit expiry in the staff record rather than relying on someone to remember a manual demotion.
Check the result
The user should receive the event group for the stated duration and retain their original groups throughout. Test both the event benefit and a normal entitlement. After expiry, confirm that the event membership disappears and the rest of the membership list matches the saved baseline.
If the result is wrong
If the user retains event benefits, look for a permanent event membership or permission inherited elsewhere. Remove only the trial’s temporary parent with the matching removetemp syntax for your release. Restore a mistakenly replaced membership from the recorded baseline; avoid clearing the whole user to rebuild one rank.
References and related help
LuckPerms maintainer reference
LuckPerms maintainer reference
Create Minecraft ranks and inheritance with LuckPerms
Trace a denied Minecraft command with LuckPerms verbose