SubForm - entering data through subform
I have a "Family" form and "Children" form. They are parent-child relationship. "Children" has a look up filed ("Family ID" field) to connect the parent form.
My idea is to display children's information when we open a family record, but I found unexpected behavior. Is it expected?
When I open one family record, I see a subform underneath. I can enter children's information. First question is do I have to choose Family ID (look up field) for each child manually? Other online database recognize what I am looking at, and entering data through the subform is connected to that family automatically.

Next question is that entering data through the subform and the regular form seem to be different. If I enter the children's information through the subform, there is no problem. Whenever I open the family information, their children's information are displayed in the subform automatically. However, children's information entered through Children Form are not displayed in the subform at all although I chose correct Family ID.
When the time for data entry comes, I want to accept both method, through the subform and Children Form.
Do you have any idea why the children entered directly on the Children form does not appear in the subform although it has correct Family ID?