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In the parent form you (optionally) can add a field that will be used to store the ID of the child form. In this example the field 'leave_details_id' has been added. This is only needed in situations where there is a 1-to-1 relationship between the parent form and the child form. You can then embed your child form in the parent form by dragging the 'Sub Form' input type form element into the section that you want the subform to appear in.
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