I'm running 2.3.2 and have created an interface with model admin to edit my data.
I also have a relation "hasmany" with other data.
This works very well.
But I want to change the order of the tabs in the edit area and I don't know how this can be done.
As you can see in the screenshot, I was searching for "Restaurants" (left navigation) .
The result was displayed on the right (edit area), after clicking on the right item, I do get
the attached screen with tab "Rezepte" as the first one.
I haven't tried it but you could remove all the fields from the tab you want last which may remove the tab, then create the tab you want first with its fields, then the tab you want next etc. It looks like you can do this and store the fieldsets in variables with FieldSet functions.