Software That Auto Put Information In Selected Line(s) in JSON or TXT File

Write a software/script that helps auto fill information in multiples Json or txt files. For example, I have a txt file which contains Username:Password Username1:Password2 and I have multiple Json files which have the something like this { "AuthConfig": { "AuthType": "ptc", "Username": "XXXXX, "Password": "Password" }, "Test": { "UseTest": false, "UseHost": null, }, The software will fill Username and Password in those Json files with Username and Password that I have in the txt file. So now, let say json 1 file will have this format { "AuthConfig": { "AuthType": "ptc", "Username": "Username, "Password": "Password" }, "Test": { "UseTest": false, "UseHost": null, }, Json 2 file will have this format { "AuthConfig": { "AuthType": "ptc", "Username": "Username1, "Password": "Password1" }, "Test": { "UseTest": false, "UseHost": null, }, Each Json file is in different folder BTW.