DockPanel Suite (C#) - How to access variables and Custom methods of Tool Window from Child Form

Question

This look like silly and similar to previous questions but it's not.

Project details: I am using Dockpanel Suite

MDIParent - Form1    testapp  
MDIChild  - Form2  child window  
ToolWindow - Form3  toolwindow  / logs

Snapshot of Test App

I want to access ToolWindow (logs window) procedures and variables from form2 (child window):

public partial class Form2 : DockContent, IForm2
{
    public Form2()
    {
        InitializeComponent();
    }

    private string m_fileName = "This is Private";

    public string _FileName()
    {
        return this.m_fileName;
    }
}

interface IForm2
{
    string _FileName();
}

and I am calling procedures of Form2 from ToolWindow using this code:

if (DockPanel.FindForm().ActiveMdiChild != null)
{
    IForm2 childForm = (IForm2)DockPanel.FindForm().ActiveMdiChild;
    MessageBox.Show(childForm._FileName() );
}

Now I want to do the same in reverse: I want to access data and procedures of ToolWindow (logs) from child window.

Found this link Dockpanel Suite and passing data across multiple forms but not working for me. My scenario is a different one.