Multitenancy with multi-Schema approach

I have some questions about multi-tenancy with a Shared-Engine / Multi-Schema approach, I saw the blog post introducing to the configuration, https://blog.flowable.org/2018/09/11/multitenancy-in-flowable/ but im my scenario i saw some difficulties.

My Scenario:
We want to have separate tenants on separate databases, and have one engine aware of all databases/tenants, with that we need to implement the Java interface TenantInfoHolder.

A implementation that we’ve seen is the Tenant by user, but for us, that does not make the cut, we want to make the same user have acess to multiple tenants.

What is the best way to archive this and does tenant used in TenantInfoHolder have a different meaning than the tenant used on the requests (ie: creating a new process)?

Thanks

A user as represented in a directory server (X.500, LDAP) cannot belong to multiple organisations (tenants).