How do I load a form on to a panel through a button inside another form?

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C#

.NET

Visual-Studio

WinForms

I have a Windows Form called Form 3. It has a side panel and a child-form panel.

The side panel has an Exam Scheduler button which loads Form 5 on to the child-form panel.

Code example,

private void profile_Click(object sender, EventArgs e)
    {
        openChildForm(new Form5());
    }

    private Form activeform = null;

    private void openChildForm(Form childForm)
    {
        if (activeform != null)
        {
            activeform.Close();
        }
        activeform = childForm;
        childForm.TopLevel = false;
        childForm.FormBorderStyle = FormBorderStyle.None;
        childForm.Dock = DockStyle.Fill;
        childFormPanel.Controls.Add(childForm);
        childFormPanel.Tag = childForm;
        childForm.BringToFront();
        childForm.Show();
    }

There's a button in Form 5. I want to learn how to code this button, so it could load another form on to the child-form panel in Form 3.

Is there a better way to achieve this other than this way?

Could someone please suggest me a YouTube video or any other site that teaches how to do this

What I have tried:

I learned to the code this form through a YouTube video. But it only explains about how to load a form on to a panel.

I don't know how to code the button in Form 5 in order to satisfy my requirement.

Please help!