can you add oxide group for who already linked so easy to give extra permission for that group

Hey, Currently this is handled by the DiscordGroup plugin.

so i need just use DiscordCore and DiscordGroup for add oxide group?

Yes, DiscordCore will do the linking and DiscordGroup will assign the roles and groups for link/unlink.

i got this when unlink / link with discord core n discord sync

[Discord Extension] [Error]: Discord API has returned error Discord Code: 50013 Discord Error: Missing Permissions Request: [PATCH] https://discord.com/api/v9/guilds/812531340099846176/members/992667887544307712 (Response Code: Forbidden) Content-Type: application/json
Discord Errors: 
Request Body:
{
  "nick": "DN デン"
}