1. You have the legal right to marry the girl who also wants to marry you,
2. However, to avoid any disturbance, it will be prudent on your part to wait till you get the appointment letter for the post of P.O.,
3. While reporting for joining the Bank, ask for distance posting to ensure that you can stay at a distance place where those people will have no commanding influence on the authority/administration,
4. After that get married in an Arya Samaj temple and get your marriage registered before a Court,
5. After that both of you can lodge a police complaint against her family members for their filing false cases/complaints and also for killing both of you. You should attach copy of your marriage certificate as an evidence of your marriage,
6. This way you shall be adequately imnunised and if they still file false cases against you, contest the cases fittingly.