When your domain model looks something like this:
You could retrieve the lists in a microflow with the use of some xpath.
Imagine that I would like to retrieve all objects A where the attribute is equal to the string x.
In the microflow add the following retrieve from the database:
To retrieve all the objects from B that are associated to the A objects the second retrieve would look like this:
And if you are not using the list of objects from A then the first retrieve is not needed and the retrieve for B and C can be performed without retrieving A, but only constraining the results for B and C on the association and attribute value of objects in A