Using both MDBottomNavigation & ScreenManager?

Question

So I'm new to kivy & kivyMD and am trying to figure out how to switch between screens. I want to use the MDBottomNavigation to switch between screens, but I also have other screens in my app that will be accessed using buttons. I'm trying to figure out how to incorporate the MDBottomNavigation with the ScreenManager. What I did was have multiple MDBottomNavigation, one for each screen. Then I would have buttons within those screens that will be used to get to other screens.

My python file:

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.app import MDApp
from kivy.utils import get_color_from_hex

class MainWindow(Screen):
    pass

class SecondWindow(Screen):
    pass

class ThirdWindow(Screen):
    pass

class WindowManager(ScreenManager):
    pass

kv = Builder.load_file("my.kv")

class MyMainApp(MDApp):
    def build(self):
        return kv

if __name__ == "__main__":
    MyMainApp().run()

My kv file:

#: import get_color_from_hex kivy.utils.get_color_from_hex

WindowManager:
    MainWindow:
    SecondWindow:
    ThirdWindow:

<MainWindow>:
    MDBottomNavigation:
        panel_color: get_color_from_hex("#02AD9C")
        MDBottomNavigationItem:
            name: 'screen 1'
            text: 'Scr1 Tab1'
            on_enter: root.current = 'MainWindow'
            MDLabel:
                text: 'Screen_1 Tab_1'
                halign: 'center'

        MDBottomNavigationItem:
            name: 'screen 2'
            text: 'Scr1 Tab2'
            on_enter: root.current = 'SecondWindow'
            MDLabel:
                text: 'Screen_1 Tab_2'
                halign: 'center'

        MDBottomNavigationItem:
            name: 'screen 3'
            text: 'Scr1 Tab3'
            on_enter: root.current = 'ThirdWindow'
            MDLabel:
                text: 'Screen_1 Tab_3'
                halign: 'center'

<SecondWindowWindow>:
    MDBottomNavigation:
        panel_color: get_color_from_hex("#02AD9C")
        MDBottomNavigationItem:
            name: 'screen 1'
            text: 'Scr2 Tab1'
            on_enter: root.current = 'MainWindow'
            MDLabel:
                text: 'Screen_2 Tab_1'
                halign: 'center'

        MDBottomNavigationItem:
            name: 'screen 2'
            text: 'Scr2 Tab2'
            on_enter: root.current = 'SecondWindow'
            MDLabel:
                text: 'Screen_2 Tab_2'
                halign: 'center'

        MDBottomNavigationItem:
            name: 'screen 3'
            text: 'Scr3 Tab3'
            on_enter: root.current = 'ThirdWindow'
            MDLabel:
                text: 'Screen_3 Tab_3'
                halign: 'center'

<ThirdWindow>:
    MDBottomNavigation:
        panel_color: get_color_from_hex("#02AD9C")
        MDBottomNavigationItem:
            name: 'screen 1'
            text: 'Scr3 Tab1'
            on_enter: root.current = 'MainWindow'
            MDLabel:
                text: 'Screen_3 Tab_1'
                halign: 'center'

        MDBottomNavigationItem:
            name: 'screen 2'
            text: 'Scr3 Tab2'
            on_enter: root.current = 'SecondWindow'
            MDLabel:
                text: 'Screen_3 Tab_2'
                halign: 'center'

        MDBottomNavigationItem:
            name: 'screen 3'
            text: 'Scr3 Tab3'
            on_enter: root.current = 'ThirdWindow'
            MDLabel:
                text: 'Screen_3 Tab_3'
                halign: 'center'

When I run the code I get an error: ValueError: KivyMD: App object must be initialized before loading root widget

What is this referring to? Is this referring to the screens because I thought they were already initialized?

Does anyone have a solution or perhaps a better way to have both MDBottonNavigation & ScreenManager? Would appreciate any feedback.