An existing_user can "invite" assign a task to a registered or to an unregistered user_worker. Existing_user will create the task record and reference user_worker by entering an email address into task.email_address.
When existing_user adds the record, I trigger a Zapier workflow. If Zapier can find the worker_user, then it updates the Task.Worker_user_ID connection to Accounts. If Zapier does not find the worker_user in the existing Accounts, it will trigger an email to invite the new worker_user to register in the Knack app.
When the user registers, we need to connect to his account all TASKS previously created that have task.email = account.email.
Zapier would let me find a task and update it; if there were only one tasks associated to an email address. Because multiple tasks can be associated to the same email, I can't find a way to update multiple records.