I think the current solution with just linking back to your forum category is a good enough solution.
In order to obtain the actual link, you'd have to write some sort of server side process to monitor the creation of new topics in the forums that relate to your blog, and the process would have to update your blog post text with the new link. Probably more effort than what it's worth or at the very least, can be tackled once everything has calmed down.
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