DevExpress TabbedView : Create Child Form from a Child Form - devexpress

Question

I'm using DX 15.1, and I'm trying to create a new tab from a child form.
So, basically, I have a parent form called "pForm", and a child form called "cForm".
I'm using DocumentManager module and switched it to TabbedView mode.
When I'm trying to create a new tab from pForm, it's totally fine.
the problem is, when I'm can't create a new tab from cForm into pForm's TabbedView.
How do I achieve this?
Thanks, mate :)
UPDATE :
#DmitryG, thanks for your response.
I've attached a screenshot below.
The MDI-Parent is the RGP page with a settings header. and the MDI-Child is the Class Attendance form (popped-up window, triggered by a button inside the RGP form).
Can you give a solution, how to make the Class Attendance Form (mdi-child) became a new Tab beside RGP tab when it's triggered by a button within mdi-parent? Not as a popped-up window.
thanks!

Answer 1

When the DocumentManager works in MDI Mode you can just work with mdi parent and child forms. So, I believe, you code for adding a new mdi-child into mdi-parent form can looks like this:
static void AddMdiChildFromMdiParent(Form mdiParent) {
Form child = new Form();
child.MdiParent = mdiParent;
child.Show();
}
Within the mdi-parent form you can call this code like this:
AddMdiChildFromMdiParent(this);
To add a new mdi-child from an existing mdi-child you can reuse the code above as follows:
static void AddMdiChildFromMdiChild(Form child) {
AddMdiChildFromMdiParent(child.MdiParent);
}