I’d need to know more about the structure of your app to say for sure. But let’s say you have a Quotation object in your HomeForm. It’s possible that you added it (with code) to your HomeForm without giving it a name. (If so, add a line like self.quotation_page = Quotation() to give it a name.) Once you can access it from the HomeForm as something like self.quotation_page, then from the UserLogin sub form you would be able to access it as get_open_form().quotation_page. So the card_user could be accessed as get_open_form().quotation_page.card_user, and so on.
For alternative approaches (and examples), see this post and the links therein: