@luistinygod
This is the solution indeed! I got it working last week, but forget to post the details.
I changed my setup so it makes more sense now (for me).
I have a accordion with 4 tabs. “Chefs Menu”, “Starters”, Soup", “Salads”. These are my post titles.
On each parent div of each tab I have a query loop with CPT “take away dishes” and I include a different type of dish ( my titles): “startes”, “salads”, “main”.
The div wich contains the content of the accordeon I query loop MB groups “menu”.
In this way I can query the header on each tab and the content when I open the tab.
On every new tab I only change the “include post” on the parent div.