Help needed smart app to operate two garage door with one app

I have two separate garage doors both are controlled by Smartthings relays and multisensors. They work great on each smart app. How to I create an app to open both doors at once? I have searched the forums but haven’t found any help. Your help will be greatly appreciated.

I am using the standard Smartthings Garage door opener smartapp. I am new to the smartthings eco system, I have been researching to understand more. I haven’t looked into CoRE yet. I will try to research this, is this a more complex smartapp?

Thank you so much for your help, I will get started!!

So I’m confused. If all you need is to control both at same time, you can just setup a routine (within the smartthings app) to open both garages at same time. You can also set a separate routine to close both. Each can be activated by 1 button push in the app or automated based upon rules. Albeit, nothing wrong with going through everyone’s recommendations to install CoRE (which is a very powerful smart app to do many,many things - but can also be overwhelming to someone just starting in home automation, IF that is your situation)

Thank you for giving your thoughts, I might do the routine for now. I started to look in CoRE and the code looks a little intense. While it looks interesting it might take me a while to master.