Zend certified PHP/Magento developer

Triple-boot Ubuntu with existing dual boot Window 7 and 10

I would like to install Ubuntu alongside my existing dual boot Windows 7 and Windows 10.

During installation of the Ubuntu “trial” it recognized Windows 10 but no mention of Windows 7. This concerned me.

I had Windows 7 originally and installed Windows 10 after. I seem to have two different boot menus, which alternate depending on which OS was last booted. Or, to be more precise, the appearance of the boot menu is different depending which OS last booted.

What is the safest way to install Ubuntu alongside my two existing OSes and keeping Windows 7 as the default OS?

Please let me know if there is any additional information I can provide.