nVision and selecting by BUDGET_PERIOD instead of FISCAL_YEAR

I have a question about budget periods vs fiscal years on LEDGER_KK as related to nVision.

The fiscal year and budget period on LEDGER_KK don't always match; the fiscal year has to do with WHEN a transaction was budget period, not WHAT the budget date is on the transaction - which could put it in a different budget period than when it was budget checked.

How can I use nVision and timespans to select from the LEDGER_KK commitment control ledgers based on the BUDGET_PERIOD field and not on the FISCAL_YEAR? Is it possible or do I need to make virtual ledgers?