Thanks for the additional info. Based on the current hierarchy for your company party IDs, there is currently active DAs for a higher-level party at this time. Fortunately, you do not need an active DA at each level of a party hierarchy; your current DAs will be able to provide access to lower level parties (They may need to select 'Full Span of Control' in order to see these details).
Additionally, a user can only be a DA for a single party ID at a time, so by adding someone to the concerned party would potentially inactivate their existing DA role. My recommendation here is to reach out to your current DA and request they fulfill any changes or modifications that are required.
