How to maintain a state in a property, which needs to be accessed from different classes in a (kind of) parent/child relationship?

Question

I have a more complex structure, where some "child" classes are added to the "parent" class as subview. Thereby I have variable called currentSelectedDate, which should be accessible in all of the connected classes. My current structure looks like the following:

Class A (top most "parent"):

private DateTime currentSelectedDate;
public DateTime CurrentSelectedDate {
    get
    {
        if (this.dayHeader != null)
        {
            return this.dayHeader.CurrentSelectedDate;
        }
        else
        {
            return this.currentSelectedDate;
        }
    }
    set
    {
        this.currentSelectedDate = value;
        if (this.dayHeader != null)
        {
            this.dayHeader.CurrentSelectedDate = value;
        }
    }
}

Class B ("child" of A/dayHeader):

private DateTime currentSelectedDate;
public DateTime CurrentSelectedDate {
    get
    {
        if (this.weekdayScroller != null)
        {
            return this.weekdayScroller.CurrentSelectedDate;
        }
        else
        {
            return this.currentSelectedDate;
        }
    }
    set
    {
        this.currentSelectedDate = value;
        if (this.weekdayScroller != null)
        {
            this.weekdayScroller.CurrentSelectedDate = value;
        }
    }
}

Class C ("child" of B / weekdayScroller):

public DateTime CurrentSelectedDate { get; set; }

Here only the direction from the parent to the child is shown, where the properties are used to spread the data. In the backwards direction I use events. The disadvantage of this approach is that I have to store the values multiple times in each class. Also if I'm in one class, I have to set the value of this.currentSelectedDate, but also in the other class (e.g. dayHeader.CurrentSelectedDate) manually (the setter/getter should only be used by external calls).

For class A the class C (weekdayScroller) is hidden.

Class C (weekdayScroller) is used by other classes too, so I have to maintain the property currentSelectedDate directly in it.

One has also to be aware of when something is initialized. E.g. on the creation of class A the currentSelectedDate is set, but class B isn't existing yet. Therefore the null checks.

My question now is if this is a good way of handling the spreading of the state between all classes or if there are better ways.

Answer 1

Is there a better way? Not that I am aware of. I understand the drawbacks of this design.

If there is just a single value of the variable to set (so parent-child relation is 1:1), why not put it in a shared class which you reference everywhere. It is virtually the same, but it might be easier to have an overview of what happens where and whose responsibility it is.