Hi Sneha,
As per my understanding,
Finance Region Location entity has two lookups ; One for Location and another for Finance region.
On change of Location lookup, finance regions needs to populated.
This can happen only if a direct relation between finance region and location is created.
Actually there exists a N:N relation between Location and Finance Region where FinanceRegionLocation is an intersect entity.
One location may be related to many finance region and vice versa.
Regards,
Rameshwari