var payloadSampler1 = { };
payloadSampler1.age = vars.get("Variable_2");
payloadSampler1.birthDate = "1980-01-01";
payloadSampler1.phone = {};
payloadSampler1.phone.number = "555-555-5555";
vars.put("payloadSampler1", JSON.stringify(payloadSampler1));

var payloadSubmit = { };
if (vars.get("someVar") != "value" && vars.get("someVar") != "value2" && vars.get("differentVar") != "true") {
    payloadSubmit.ageInfo = [${payloadSampler1}];
}
if (vars.get("someVar2") != "true") {
    payloadSubmit.paymentInfo = [${payloadSampler2}];
}
payloadSubmit.emailInfo = [${payloadSampler3"}];
payloadSubmit.country = vars.get("Variable_3");
vars.put("payloadSubmit", JSON.stringify(payloadSubmit));

Variable_1=ABC
Variable_2=DEF
Variable_3=GHI
payloadSampler1={"age":"18","email":null,"name":{"firstName":"Charles"}},{"age":"38","email":null}}
payloadSampler2={"paymentChoice":{"cardType":"CreditCard","cardSubType":"VI"}},"amount":"9.99","currency":"USD"}
payloadSampler3={"email":"tes@email.com"}
payloadSubmit={"ageInfo":[{"age":"18","email":null,"name":{"firstName":"Charles"}},{"age":"38","email":null}],"paymentInfo":[{"paymentChoice":{"cardType":"CreditCard","cardSubType":"VI"}},"amount":"9.99","currency":"USD"],"emailInfo":[{"email":"tes@email.com"}],"country":"GHI"}

Variable_1=123
Variable_2=456
Variable_3=789
payloadSampler1={"age":"95","email":null,"name":{"firstName":"Sam"}},{"age":"12","email":null}}
payloadSampler2={"paymentChoice":{"cardType":"CreditCard","cardSubType":"DC"}},"amount":"19.99","currency":"USD"}
payloadSampler3={"email":"tes2@email.com"}
payloadSubmit={"ageInfo":[{"age":"18","email":null,"name":{"firstName":"Charles"}},{"age":"38","email":null}],"paymentInfo":[{"paymentChoice":{"cardType":"CreditCard","cardSubType":"VI"}},"amount":"9.99","currency":"USD"],"emailInfo":[{"email":"tes@email.com"}],"country":"USA"}