I'm not sure I understand the issue then. From the forum editor when I'm replying, I can create the link - here's an example that will point back to this forum.
I think maybe you're looking for the TOPIC REDIRECT add-on which should be part of your platinum subscription already. Check to see if it's activated.
If it is then these two links should help you see what it does and how to use it:
Please let me know if this is what you're looking for.