It's better not to put links in headlines with subs. It makes clicking on the headline have two meanings, and this can be confusing. If I find I want to add notes under something that's already linked, I add a new headline, and moved headline with the link under it.
If you want something to be in the feed, you have to use the + icon to create it. Some people are apparently creating new items by pressing Return. I do it myself, without thinking. Those items will not be in the feed.