One-to-Many NSFetchedResultsController with as much rows as the relationship NSSet contains

I'm trying to set up a tableView like so:

-Family
--Person 1
--Person 2
--Person 3
-Family 2
--Person 1
--Person 2
--Person 3
-Family 3
... etc

I have no problems getting the sections populated with the family names:

- (NSFetchedResultsController *)fetchedResultsController:(NSString *)forEntity sortyBy:(NSString*)sortAttribute sectionName:(NSString *)sectionName {

if (fetchedResultsController != nil) {
    return fetchedResultsController;
}

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:forEntity inManagedObjectContext:[self managedObjectContext]];
[fetchRequest setEntity:entity];

NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:sortAttribute ascending:YES];
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
[fetchRequest setFetchBatchSize:20];

NSFetchedResultsController *theFetchedResultsController = 
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:[self managedObjectContext] sectionNameKeyPath:sectionName cacheName:nil];

self.fetchedResultsController = theFetchedResultsController;
self.fetchedResultsController.delegate = self;
return fetchedResultsController;
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return [self.fetchedResultsController.fetchedObjects count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section 
{
id <NSFetchedResultsSectionInfo> sectionInfo = self.fetchedResultsController.sections[section];
return [[[sectionInfo objects] objectAtIndex:0] name];
}

However filling in the rows containing the persons is proving difficult for some reason.

There is a One-to-many relationship active that provides Family with an NSSet attribute called "Persons".

How can I return a correct count on the number of persons in that set and then set the cells accordingly with the Persons' data?

I tried altering the numberOfRowsInSection method in numerous ways but can't seem to find a non-crashing way of accessing the Family. Persons NSSet here to count them.

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
id <NSFetchedResultsSectionInfo> sectionInfo = self.fetchedResultsController.sections[section];
return [sectionInfo numberOfObjects];

}

Should I be using something other than an NSSet or even NSFetchedResultsController in a whole?

Important is that I will place "2 segmentedControls" above the tableView. This will allow some deep filtering but for that to work I need to be able to fill sections and corresponding rows depending on what the user selects to filter on.

For example:
SegCtrl 1: User selects Family, SegCtrl 2: User selects age.
This draws a UITableView with the available Family names as sections and as rows all the ages of the Persons in that Family.