Proper way to run multiple hydration query with doctrine and querybuilder

Question

I am having an issue running a query with multiple nested joins. I discovered that doctrine has a problem where if you run a query with more than two joins it quickly becomes very expensive.

I found an article here: https://ocramius.github.io/blog/doctrine-orm-optimization-hydration/ describing the solution via multiple hydrations technique, however I am running into an issue when I attempt to run the query. I can't seem to get my partial right so that my second query is running off of the pre-existing hydrated data from the first query.

basically I need to be able to join the result off of the hydrated data ca.member (which is an array)

Here is my Query:

//first query to grab and hydrate data
$qb = $this->createQueryBuilder('ca');
        $case_alterations = $qb->select('ca, cg, cma')
            ->innerJoin('ca.gene', 'cg')
            ->leftJoin('ca.mask', 'm')
            ->leftJoin('ca.member', 'cma')
            ->where('ca.case_id = :case_id')
            ->andWhere('m.id IS NULL')
            ->setParameter('case_id', $case_id)
            ->getQuery()
            ->getResult()
        ;

//second query should grab the already hydrated data in memory and perform the join
        $query = $this->createQueryBuilder('ca')
            ->select('partial ca.{member}, cr')
            ->leftJoin('ca.result', 'cr')
            ->getQuery()
            ->getResult()
        ;

And here is the error I keep hitting because its referencing case from the first query rather than the subset, member:

\Entity\Case has no association named result