Hey Ingrid,
It is possible to do what you are trying to do, but the specific code changes required to do that are unfortunately a bit more complicated than the code snippets shared in the forum thread you linked to above.
I’m sorry about this! If this is a feature you really need, and you are willing to hire someone to build this feature for you, then one thing that might be helpful is this list of Customizers that we maintain here → http://m.tri.be/18k1
We have no affiliation with those folks, but they’re some well-respected developers in the community that could be hired to build something like you describe here.
I’m sorry to disappoint but wish you the best of luck with your customizations.
Sincerely,
Gerge