Trouble with the menu Block module I am trying to build pages with the main menu displayed in multiple locations. A "main navigation" with top-level items A,B,C,D,E; and each of these has children a1,a2,...b1,b2,... etc.

There is a drop-down navbar menu in the header that is on every page (that displays A B C D E and when you click on any one of them, it shows its children); if you click on any child (say a2), it takes you to a url .../A/a2. That page still has the "main navigation" in the header, but also in the left sidebar it has the sub level menu of A (a1,a2,a3...) with a2 highlighted.

Someone directed me to try the menu block module, but i am not able to get it to display just A's children while in A. Depending on the options I choose for depth etc. I can either show all links (A B C D E a1 a2...e1 e2...) or all the children from all the parents (a1,a2,...,b1,b2,...,e1,e2...).

Using twig debugging, I see it's using the same template as the navbar drop-down menu, so I can't write a separate template either (or can I?)
Ok, I sorta figured this out. It might be a hack, but if I start with initial menu level: 1, maximum menu levels to display: 1 and fixed parent item to be the menu who's children i want displayed, then it sort of works.

Only caveat is I need to make a separate block for each separate child of the menu. Plus, it is still using the same template to display the menu in both places (header + sidebar). Perhaps using custom blocks and changing its name will generate a new template?

I'd love to hear a better answer if there is one.