Actual vs Plan on different grain

Hello I have to prepare model for new datamart and I encountered following problem:

I have a snapshot(weekly snapshots) fact table like this one:
date_id
branch_id
prod_id
segment_id
amt
plan

and hierarchies like this one:

dimension product
prod_id
prod_nm
prod_grp_id
prod_grp_nm
main_grp_id
main_grp_nm

The problem is that the plan could be defined on any aggregation level (for example plan for branch 1 and prod_grp_id=2 is 200, Plan for branch 2 is 300, Plan for Branch3 and prod_Id=4 and segment_id=4 is 400). Not on the lowest grain!

Does anyone knows how to design fact and dimension tables to get this working?

This is typical... it is rare that a company plans at the lowest possible level.

Actuals need to be rolled up to the plan level. You usually have two fact tables, one for actuals (i.e. detailed sales facts) and one for budget/plan.