Is it obligatory for children to work with their father in his commercial insurance company to please him, despite their unwillingness to do so due to the legal rulings (fatwas) related to this field?

Obeying parents is obligatory unless they command disobedience to Allah, or something harmful, or something unbearable. It is not permissible to work with the father in commercial insurance, which is forbidden in all its forms and types. Therefore, there is no sin in not obeying him in this matter.