forwarding SMS to another number and replying from that other number

Hello,

I was just wondering how I can reply from another number but have it go through the twilio number or if that is even possible. I have already set up a flow to have the messages sent to the twilio number be forwarded to a JustCall number and that is working fine. But when I try to reply from the JustCall number, my own reply forwards to the JustCall number and never reaches the number that I am trying to reply to.