Restrict values within a custom value set based on cost center information

Created a custom value set based on Table search:

Need to restrict the values within the value set based on Legal Entity or original Cost Center SVS rules (as there are SVS implemented). Would this be possible?

The other option is to have a context sensitive segment on the EXM_ADVANCES flexfield within Expenses, but cannot find what the context should be within the Cash Advances page to use for Cost Center ? There are only two legal entities / structures (this would be the two segments within the context)