Multi hierarchical modeling

Power BI data modeling question – multiple deep account hierarchies

I’m looking for the best data-modeling approach in Power BI for the following scenario.

I have a DimAccount table that contains 5 separate hierarchies, each with ~15 levels, stored in a flattened format:

• Hier1Level0 … Hier1Level15
• Hier2Level0 … Hier2Level15
• …
• Hier5Level0 … Hier5Level15

My Fact table is very large (~1 billion rows) and contains an AccountKey as a foreign key (along with ~10 other dimension keys).

Requirement

• I need to display all hierarchies together:
  
• In a single slicer
• And in a single matrix visual
•  
• Without using field parameters

Approaches I’ve considered & issues

1. Unpivot / normalize hierarchies (horizontal → vertical)
   
• This duplicates AccountKey in the dimension.
• Results in a many-to-many relationship with the fact.
• Requires a bridge table with bi-directional filtering.
• Breaks the clean star schema, and I’m concerned about performance and model complexity given the fact size.
2.  
3. Split each hierarchy into separate role-playing dimensions
   
• Maintains a star schema.
• However, I cannot combine all hierarchies into:
  
• One slicer
• Or one matrix visual
•  
4.  

Question

What is the best-practice modeling approach for this scenario that:

• Scales well with a very large fact table
• Allows all hierarchies to be used together in slicers and matrix visuals
• Avoids field parameters
• Minimizes many-to-many relationships and bi-directional filters where possible

Any guidance or recommended patterns would be greatly appreciated.