get many backreferences to one node and then more backreferences to those nodes

I've been looking for solutions to do the above and ended up putting a query in a views nid-field (with no relationship) template file because I couldn't figure it out with either of your modules. I ended up with this monster of a query:

$query = <<<EOT
SELECT nodes_derived.nid FROM (
  SELECT DISTINCT node.nid AS nid
  FROM node node
  LEFT JOIN og_ancestry og_ancestry ON node.nid = og_ancestry.nid
  LEFT JOIN content_field_system_req_reference content_field_system_req_reference ON node.vid = content_field_system_req_reference.vid
  LEFT JOIN casetracker_case casetracker_case ON node.nid = casetracker_case.nid
  WHERE (
    og_ancestry.group_nid =1
  )
  AND (
    content_field_system_req_reference.field_system_req_reference_nid IN (
      /* Subquery to find system requirement nodes that reference to this user need */
      SELECT nodes_derived.nid FROM (
        SELECT DISTINCT node.nid AS nid
        FROM node node
        LEFT JOIN og_ancestry og_ancestry ON node.nid = og_ancestry.nid
        LEFT JOIN content_type_requirement node_data_field_user_need_reference ON node.vid = node_data_field_user_need_reference.vid
        LEFT JOIN casetracker_case casetracker_case ON node.nid = casetracker_case.nid
        WHERE (
        node.status <>0
        )
        AND (
        og_ancestry.group_nid =1
        )
        AND (
        node_data_field_user_need_reference.field_user_need_reference_nid =%d
        )
      )nodes_derived
    )
    AND (
    casetracker_case.case_status_id =5
    )
  )
)nodes_derived
EOT;
$tasks = db_result(db_query($query, $output));

Is there any way you can do a double subquery like this with a module? because I already forgot how I came up with this code so it is not a maintainable, nor a portable solution. (but it does work).

Also feel free to comment on my code because I have a theming background and I'm new to this.