After I saw this topic, I thought it was the right time to request this feature. This is happening a lot, especially in communities where users try to find a way to start a heated discussion. Quoting a post is an effective way to do that, especially when altering the original text.
Quoting a post gives you the ability to post someone’s reply altered. Although the following example is a bit extreme, I have witnessed similar things in the past:
Once you press the show more button, it does sometimes highlights only the quoted text. However, ones has to do that in order to understand whether the quote is the same or not.
The most important thing is that if user A deletes their post, user B, who has quoted and alerted the post of user A, will be able to keep their post, without the other members know whether it was the original one or not.
Therefore, I am suggesting a small feature. If user B quotes user’s A post and alters it, a small notice would appear next to the quote indicating that it is not the original one and has been changed by user B. That could be an icon, such as the orange edit pencil or a small warning: