No need for a change. The facility already exists.
At the top level of your forum go to: OPTIONS > APPLICATION > EXTRAS & ADD-ONS > CONTENT > CUSTOM SUMMARY FOR NEWSPAPER and check the box there.
You can then enter something like this at the top of your article:
{summary_start}Summary begins. <a href="http://domain.com/">Link Text</a> Rest of the summary.{summary_end}
The text between the {summary} tags will be used as the article summary instead of the first 300 characters of the body of your post. Another advantage of using this customised summary technique is that you can use HTML entities in your text so, for example, copyright symbols will be properly rendered.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.