Subscribe to the FHumpires webcal and get them all in your calendar app with a couple of clicks (and remove them all just as easily!) Time zone encoded and EVERYTHING.
There will also be little nuggets for umpires showing up from time to time–appointees, live chats, and more. Remember, your calendar app can hide the display of these events whenever you need to, and you can always delete the calendar if it doesn't suit.
Don't know what the heck a webcal is? It's a web standard calendar that works with Apple Calendar, Google Calendar, Microsoft Outlook and Mozilla Lightning, adding events as a live feed into your app on a separate calendar for easy searching and filtering. Just google something like “add subscription calendar (your app)”. If you're stumped, just send me a note on social media or here and I'll be happy to lend a hand (I'm geeky like that!).