Since many days I was trying to perform few logics over LedgerDimensions and DefaultDimensions, like merge and replace etc. In AX2012 its handled by DiemsionDefaultingService class that having many static method to help us to play around ledger/default dimensions.
But in Dynamics 365 FO , this class is deprecated, and MS introduce few more classes to help us with these requirements. Here are few name of classes and method that can be used.
1. LedgerDimensionFacade : This class used for fixed LedgerDimension, we have many static methods here, like Merge Dimension, getdefaultDimension and many more, refer below image.
2. LedgerDimensionDefaultFacade: This class will help us to perform action over default dimension. Like Merge specify default dimension into single default dimension, replace attribute value etc.
Please refer below image,
Both classed having almost same method that is available in AX with DiemsionDefaultingService class.