New Guy 74,
First of all, there are no stupid questions and, as it turns out, your question has been asked by various users over the years.
My take on the issue is this. In a good Project plan each and every task should be unique. There are no duplicates. Furthermore, summary lines are not tasks at all (even though they are called "summary tasks"). They simply categorize or summarize the activities
(subtasks) under them. Those activities should be expressed in action verb format describing something that is accomplished using one or more resources. I like to refer to subtasks as "performance tasks" since the assigned resources perform work to complete
the task.
In your particular case the "promote ourselves..." sounds more like a summary line that should contain specific development of articles for various media. For example, the first subtask might be "Write article for local newspaper". Another subtask might
be "Create Facebook page". Another, "Send out weekly tweets". Those are performance tasks that can be assigned to a resource and can be measured to know when they are done.
By organizing the plan in that fashion, you might find that "customer relations" are automatically addressed by the above performance tasks but if there are other specific activities you could perform for your customer, then those can be shown under a separate
customer relations summary.
But to answer your original question, yes there are ways to "mirror" tasks within a Project file but they are not necessarily straightforward.
Hope this helps.
John