221g given after drop box

Hi everyone
Me and my wife while we renewing our b1/b2 visa along with fresh application for our 2 minor kids at mumbai consulate , we both are eligible for interview waiver program, so that went to give biometric and submitted all four application, me and my wife got visa and for my kids given 221 g blue slip to attend interview with out appointment, if it really refused for my kids i don’t like to appeal on visa officer decision , but they want confirm something from me definitely i like to attend interview
Pls if somebody experienced same type of issue any idea about this pls let me know, thank you