The antonyms for the phrase "checking upon" are ignoring, neglecting, and overlooking. To ignore means to intentionally disregard or pay no attention to someone or something. Neglecting means to fail to care for or attend to someone or something properly. Overlooking means to fail to notice or give attention to something. These antonyms signify a lack of interest in the well-being of someone or something. While checking upon requires active involvement and concern, these antonyms suggest a passive or indifferent approach. It is important to pay attention to these antonyms to avoid any negative consequences that could arise from neglecting or ignoring important matters.