How to create a Custom Menu after Object in the View 3D Header

Question

I am trying to create a custom entry just after the "Object" menu of the 3D View, but I can only append or prepend it, meaning it is at the begining or at the end of that particular space.

Here is the code:

import bpy

class BlablaMenu(bpy.types.Menu):
    bl_label = "blabla"
    bl_idname = "VIEW3D_MT_blabla_menu"

    def draw(self, context):
        layout = self.layout            
        layout.operator("object.text_add")

def draw_item(self, context):
    layout = self.layout
    layout.menu(BlablaMenu.bl_idname)

def register():
    bpy.utils.register_class(BlablaMenu)
    bpy.types.VIEW3D_HT_header.prepend(draw_item)

def unregister():
    bpy.types.VIEW3D_HT_header.remove(draw_item)
    bpy.utils.unregister_class(BlablaMenu)

if __name__ == "__main__":
    register()

I am aware of similar questions, but the answers are outdated. I also tried to understand how RetopoFlow and Boxcutter are solving this problem, but I can't find the code that draws those menus in order to reverse engineer it. Another approach would be to remove all the menus, create my own and re-create te deleted menus, but I don't know how to do that either.

Thank you and happy new year!