Runtime LOV in Document of Records

Runtime LOV required of Document of Records.
LOV1 contains the records of DOR where all the records are recorded.
LOV2 contains must be depend on a value from runtime and filter the LOV1 based on the record.

Lov1 Select 1 Value: Based on Valueset, LOV2 must be filtered.

Example:

Lov1: Pakistan:
Lov2: [available option of "Pakistan"] - Sindh, Punjab, ...

Lov1: United States:
Lov2: [available option of "United States"] - California, Taxes, ...