Yes, there are different ways you can do this for ease, and just like @Patrick_Hunt , we use Teams (rather than slack) for conversations related to projects.
Here are couple of ideas as well:
You build your project in a board view and the three tasks you mentioned above you make them into 1 task only. You have a custom field to shift between the stages, and you can create a rule to change the assignee once the task moves from one stage to the. next. This way all the comments are in the single tasks. Why board view, because you can move the tasks from one column to the next and include that in your rules as well. This way you can see the task progress.
In the example above you create a single task and you can mark it a milestone or an approval, and you list the three tasks underneath this major task. So the three tasks are now subtasks. You assign each subtask to the respective person. You create a team rule that only tasks are to be used for comments and questions. Subtasks are not to be opened in this project - so you only use the first layer. This way all comments can be visible under each other.
I hope this helps.
Rashad