Tanveer Madan

Hi, I have applied for extension of B2 visas for my parents and the application reached the Lockbox in Texas on 1-Feb-2021 But until today my check for application fees in not deposited and I have not received the receipt number Their I94 expires on 25-Mar-2021. Can they stay in US if I do not receive the receipt number by then or should I apply online? Thanks, Tanveer