While Nikhat blanked Haryana's Minakshi 7-0 by a unanimous decision, Lovlina outclassed Railways' Pooja by an identical margin.
The six-time world champion injured herself in the first round of the semifinals of the selection trials.
The other six boxers who made their way into the Indian team include 2018 bronze medallist Mohammad Hussamuddin (57kg), Rohit Tokas (67kg), reigning national champion Sumit (75kg), Ashish Kumar (80kg), Sanjeet (92kg) and Sagar (92kg+)
The Telangana boxer out-punched her opponent from Thailand in the final of the Women's World Championships in Istanbul.
Nikhat, the 2019 Asian Championship bronze medallist, made short work of Brazil's Caroline De Almeida to notch up a dominant 5-0 win. She will take on Thailand's Jitpong Jutamas on Thursday.
Nikhat out-punched England's Charley-Sian Davison 5-0.
Zareen outpunched Mexico's Herrera Alvarez 5-0, while Parveen defeated Ukraine's Mariia Bova by a similar margin.
This is Lovlina's second win over Chen. The Indian had got the better of her in the Tokyo Olympics quarterfinal enroute to her bronze medal-winning performance.
The Irishwoman, who stretched her unbeaten professional record to 21-0, and Serrano were the first women to headline a fight at the Madison Square Garden.
Tyson Fury emerged unscathed from a turbulent fight week to cement his place among the greats of heavyweight boxing with a stunning TKO win over Dillian Whyte.