We need to define a many-to-many relation between DimAccount and DimCustomer. This can be done using a bridge table.
Note: Relate many-to-many dimensions
The classic many-to-many scenario relates two entities, for example bank customers and bank accounts. Consider that customers can have multiple accounts, and accounts can have multiple customers. When an account has multiple customers, they're commonly called joint account holders.
Modeling these entities is straight forward. One dimension table stores accounts, and another dimension table stores customers. As is characteristic of dimension tables, there's a unique identifier (ID) column in each table. To model the relationship between the two tables, a third table is required. This table is commonly referred to as a bridging table. In this example, it's purpose is to store one row for each customer-account association.
Reference:
https://learn.microsoft.com/en-us/power-bi/guidance/relationships-many-to-many