TL;DR
Use the parent list to check accepted connections and the children linked to each parent.
Steps
Open Parents in Insights for the relevant school year.
Search for the parent by name or invited email.
Open the record and review the connected children.
If a link or address is wrong, verify it with the family before using an available management action or contacting support.
A missing parent record may mean the invitation was never accepted. Begin with the student's sharing flow instead of asking the family for a school code. Parent access is read-only and excludes private tasks.
Related help
Invite a parent while keeping your privacy · A parent invitation is missing or does not work · Manage weekly summaries and parent access