I use the below code to sort List<DataAccessViewModel> list.

Here is the sort order :

1. PriorityScore
2. MName
3. CName
4. FName

It works as expected.

public int Compare(DataAccessViewModel x, DataAccessViewModel y)
{
    if (x == null || y == null)
    {
        return 0;
    }

    return x.CompareTo(y);
}

public int CompareTo(DataAccessViewModel mod)
{
    int retval = (int)(this.PriorityScore?.CompareTo(mod.PriorityScore));
    if(retval != 0)
        return retval;
    else
    {
        retval = (this.MName ?? "zzzzzzzzzzzzz").CompareTo(mod.MName ?? "zzzzzzzzzzzzz");
        if (retval != 0)
            return retval;
        else
        {
            retval = (this.CName ?? "zzzzzzzzzzzzz").CompareTo(this.CName ?? "zzzzzzzzzzzzz");
            if (retval != 0)
                return retval;
            else
                retval = (this.FName ?? "zzzzzzzzzzzzz").CompareTo(this.FName ?? "zzzzzzzzzzzzz");
        }
    }
        
    return retval;
}

But the code looks clunky to me. Is there any better way of doing it or is this it ?