Hi @Mandy_Ford,
Yes, Flowsana’s Dynamic Duration Workflow type will do exactly what you describe here.
You would be the only one who would need to have a Flowsana account. In terms of billing, Flowsana uses a similar philosophy as Asana - the Flowsana cost is $2.99/month for each Asana user in teams having workflow-enabled projects (Flowsana calls these “billable users”). So the others in the project would be billable users since they are getting the benefits of Flowsana’s automation - but they don’t need to have Flowsana accounts.