> ## Documentation Index
> Fetch the complete documentation index at: https://www.plain.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# addMembersToTier

> Adds one or more tenants or companies to a tier (up to 25 per call). Because each tenant or company can belong to only one tier at a time, adding a member that already belongs to another tier will move it to this tier. Requires the `tierMembership:read` and `tierMembership:create` permissions.