Save a new record through a pivot table with three foreign keys in Laravel with Eloquent

I created the database design https://i.stack.imgur.com/PGOy9.png and I'm a bit concerned about the right-side part, the surveys,questions, answers and answer_question_survey tables.

What I want to accomplish

Scenario 1: List all questions with their related answers.

That should be possible with e. g.:

$project = Project::with([
    'surveys' => function ($query) {
        $query->where('name', 'project-contract');
    },
    'surveys.questions' => function ($query) {
        // no constraint
    },
    'surveys.questions.answers' => function ($query) {
        // no constraint
        // answers uses a hasManyThrough relation towards the questions model.
    }
])->where('id', 1)->get()->toArray();

Scenario 2: Answer a specific question.

This is the use case where I can't find a proper solution. First I would like to give an answer, e. g.:

$answer = new Answer();
$answer->answer = "I am an answer.";
$answer->save();

In a second step attach the answer to the related question in the related survey. Here I can't figure out a proper solution. Maybe my database design approach is bad. If so, please share your ideas for an optimization. Maybe the way I would like to realize scenario 2 is not good. Again, please share your ideas if you think that this is the case.

If the design is fine, please share your ideas to accomplish the second scenario.