How do I build something once and reuse it in all my sub-accounts?

Use snapshots. A snapshot is a template: you choose which items go in it and save it.

1. Open Snapshots (in the Library) and create a snapshot.
2. Give it a name.
3. Select the items you want in it. You can include just about anything, for example agents, automations, auto replies, custom fields, forms and funnels.
4. Save it.

Then either apply it to a sub-account with Apply to subaccount, so the client gets those items, or attach it to a SaaS plan in the SaaS Configurator, so everyone who gets that plan has their account pre-populated with it automatically. You build once and sell the same system over and over.

Snapshots have version control, with granular control over what counts as a minor or a major version, so you can push later changes down to your sub-accounts.

For emails, the email section also has an import feature. Because the AI is good at building, you can also paste an old email (a screenshot or its HTML code) and tell the AI agent to create it.