Plan a Floodgate username-prefix change without splitting player identity

A Floodgate name prefix helps distinguish Bedrock names from Java names. Changing it on an established server can confuse plugins that store names, permission targets or display labels. It is an identity migration, even if the player-facing change looks cosmetic.
Record the starting point
Record the present prefix and pick one consenting Bedrock tester with known homes, claims and permissions. Note the tester's UUID from a trusted server record. Back up the world and identity-dependent plugin data, including their databases where applicable.
Work through the change
Inspect which installed plugins use UUIDs and which rely on player names or commands containing names. List the rank, claim, economy and teleport integrations the tester actually uses.
Trial the prefix change on a private server copy using the installed Floodgate release's documented configuration. Do not change authentication type or account-linking policy during the same trial.
Join with the same Bedrock account and compare its UUID, inventory, balance, homes and claim membership. Rejoin with a Java account whose display name could be confused with the new format.
Update only the name-based integration entries that the documented migration requires. Keep a mapping from old visible names to verified UUIDs so staff do not create replacement accounts by guesswork.
Check the result
The same person should retain the same intended data and permissions, while staff can still distinguish identities. Check console commands and moderation searches as well as chat appearance. Record any plugin that needs a separate migration before scheduling the live change.
If the result differs
Missing data does not prove it was deleted. Stop the trial and inspect the UUID and account-linking state before creating a new record or copying inventories. An online-mode change can introduce a second identity problem that hides the original prefix issue.
Return to the saved prefix and configuration if any identity-dependent feature fails. Restore affected plugin data only from a matching checkpoint if the trial wrote incompatible records; do not merge player folders or database rows without a documented migration.
References and related help
Floodgate maintainer reference 1
Floodgate maintainer reference 2
Set up Geyser and Floodgate for Java and Bedrock crossplay
Back up game files before making changes