I breaks some OOP principles, but you could call your child forms with a reference to the parent form, then you have access to the parent methods and properties:

* Call the child form
do form MyChildForm with thisform

* Init section of child form
lparameters loParentForm
thisform.createproperty('oParentForm', loParentForm)

* From Child Form, samples of method or propertie access
thisform.oParentform.MyMethod()
thisform.oParentForm.MyProperty = NewValue