> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://familypro.crisp.help/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# What does Duolingo "Invitation Link Expired" Mean?

This usually happens when multiple accounts are added to one order, causing the family group to be full. Please contact customer service to remove extra accounts, and you can join again.