Create Fake Month List for only the time periods that you need in your drop-down:
Then Make a module for mapping real-time to fake time. Fake time will be your dimension, and Real-time (Months) will be the format of the line item):
Then Make a line item for your time selector that is formatted as your fake list. (This is where the end user will select from a drop down)
Then there are a few ways to do this step, but the most straight forward would probably be to have 2 lines items. One for CY Lookup and one for PY lookup.
Then in your variance module, you can reference these 2 line items as your lookup:
PY = Data Module.Data[LOOKUP: PY Time Lookup]
CY = Data Module.Data[LOOKUP: CY Time Lookup]
This would need to be manually updated annually to keep the time periods correct unless you got creative with how this list is created, But if I am understanding your question correctly, then it should work.
This looks good but are there any restrictions to it because I have used Timesum function for the calculations of FTM, YTD, DTG & FY. I am getting correct number in FY but it displays no data for FTM & YTD.
The module from which values are flowing has no timescale & timerange as it uses the Timesum function but the back end module from which it refers values has the anaplan time period "month" & refers to the manually created time range of 2years in the model.