Peace be upon you. It is sufficient to inquire about your relatives through WhatsApp, as long as you maintain the connection and check on their well-being occasionally, while adhering to Islamic guidelines. You can fulfill your duty of maintaining family ties by asking about them and sending messages, rather than needing to visit in person. According to Ayatollah Khamenei, as long as relatives do not sever ties and support each other, they have fulfilled their obligation. Similarly, Ayatollah Sistani states that maintaining contact, even through phone calls, is sufficient, and visiting is not mandatory. Asking about someone through another person also counts as maintaining family ties. May you be successful in all good deeds.