Storing common data across tenants in NoSQL databases like mongoDB

We are designing a multi-tenant architecture. In our multi-tenant architecture, there are different email templates that are shared across all the tenants.

Email template looks like

subject: {tenantName} welcomes you. body: Hi {userName} welcome to the new platform.(Generic template).

But a tenant can have their own specific email templates as well.

subject: {tenantName} welcomes you. body: Hello {userName}/{userEmailId} welcome to the new journey and thank you for joining us.(tenant specific template).

For multi-tenancy, we are using a different database for each new tenant. Now the question arises of how to store the email template keeping in mind that the template for welcoming (in this case) may be tenant-specific and if the tenant has not configured then the generic template will be used. In which collection should one keep these templates?