You cannot directly edit an embedded form within the context of the parent form. It is possible to move it to a different location within the form, but it cannot be edited directly.
Procedure
In the Form Designer canvas or Outline view, select the embedded form pane.
Go to the Properties tab in the Properties view of the embedded form pane. The Form Reference displays a link to the embedded form.
Click the link to open the embedded form in the Form Designer.
Click the ellipsis (...) button to change the embedded form.
Update the embedded form using the Form Designer.
The updates are available in the parent forms without having to re-embed the form.
Note: The changes made in the embedded form can be seen in preview and at runtime after the parent form is redeployed.