def merge_qs_maps(obj1, obj2):
    """
    Merge queryset map in `obj2` on `obj1`.
    """
    for model, [qs2, fields2] in obj2.items():
        query_field = obj1.setdefault(model, [model.objects.none(), set()])
        query_field[0] |= qs2            # or'ed querysets
        query_field[1].update(fields2)   # add fields
    return obj1