2 companies, 1 ledger or 2 ledgers?

Hi everyone.  We have an existing UK ledger with subledgers and the ask is for another company# (balancing segment) and ledger to be set up for another UK entity.  There will be no people here and no subledgers are required.  It will only have journal entries from time to time.  I'm thinking this new company could just be added to the existing ledger.  There's no difference in chart of accounts, currencies, or where it should consolidate to.  Is there anything that we lose out on by putting it in the same ledger?  I'm not sure if retained earnings are calculated