TYPO3: How do I insert page content into template

Question

I have some content that I want to appear on multiple pages of my TYPO3 site. I could just insert this into the template, but I also want that content to be editable in the

Answer 1

From Include typo3 content elements on every page:

temp.foo = RECORDS
temp.foo {
    tables = tt_content
    source = ID # Enter the object's ID here
}

Note the ID is the content record ID, not the page ID.

But that doesn't answer the question of how to only include pages/records with a certain parent.