Just some general information that I reference often that might help.
This post contains lots of nice info on “reaching back” to parent forms to access their components. You can also store methods on forms and “reach back” to call them. In your case, having looked very quickly, you may need to do some of this to access the parent form/component.
You may also search the forum for related terms (like parent form, outer form, get_open_form, etc…).
I hope this helps to point you in the right direction.
Also see this post which connects to many related threads and ideas that deal with accessing functions that live outside the current form.