How should BloC be structured in Flutter?

Question

I'm new to BloC and Flutter. For a single simple screen it should works without problem. But let's take a look at my case, I'm confused on how to use the BloC pattern.

I have a single screen called Container, which container a PageView of Content screen. Say I have 5 pages within that PageView. These pages count is dynamic. The pages only differ the data.

I'm thinking about 2 ways of implementing this:

1/ Using ONE single bloc and pass it to my 5 child Content.

2/ Using one bloc for the Container and another bloc for the Content. So this seems to be nested blocs. the ContainerBloc will contains the list of ContentBloc.

For the 1st approach. The problem that I see is the re-rendering problem. I will create a list of data of each page:

List<List<String>> allData = [];
BehaviorSubject<List<List<String>>> _allData = BehaviorSubject<List<List<String>>>();

Observable<List<String>> getData(index) => _allData.stream.map((list) => list[index]); //This stream returns the list at the index

and each page will listen to the data by:

//StreamBuilder in the UI
stream: widget.bloc.getData(index);

and the update method for the data should be like:

void updateData(int index, List<String> newData) {
    List<String> temp = allData[index];
    temp.add(newData);
    allData[index] = temp;
    _allData.sink.add(allData);
}

As I understand, once one page is updated. All other page will re-render because they all listen to the getData(index) stream which will be triggered by the_allData.sink.add(allData); So I think all pages will be re-rendered even though the data of that page is not changed.

For the 2nd approach. I don't know if it would be best practice to have nested bloc like that. There maybe some case when the ContainerBloc must listen to some of the ContentBloc output.

I'm kinda confused now.

Thank you for your time.