Do not reply to each post individually. This creates the bumping infractions. Since each new post "bumps' your thread back to the top of the forum message que.
When responding to multiple people..click the quotation marks at the lower right corner of the post.
Here's an example:
Once you've clicked the quotation marks for the posts you want to respond to go to the bottom of the thread and click the reply button.
This brings you to a new screen where you can respond to each post.
Now type your desired response
Once your ready to post it - click the submit reply button and your post will be added to the thread.