Find my IPhone

Since iCloud Family Sharing is enabled, that Find My iPhone for the entire family is enabled. You can then easily locate your family member's devices without messing around with Apple ID.

If you find this a concern, you may disable Family Sharing.

Family Sharing - Apple Support

This is what Apple says for the issue you mentioned:

Find everybody’s devices.

Finding your family’s lost devices is even easier now that everyone can help. With Family Sharing and Find My iPhone, any family member can help locate another member’s missing device. Their devices appear in a single list in the Find My iPhone app on iCloud.com on any Mac or Windows computer, or on your iPhone, iPad, or iPod touch. So it’s easier than ever to track down a misplaced or stolen iPhone, iPad, or Mac.

MrPhomys wrote:

Hello,

Recently we found out that it is possible to erase an iPhone/iPad with search my iPhone with another account that is not even mine. I have added my dad in search friends and share location. It was he who found out that he could erase my iPhone/play a sound or put it into lost mode. We both have different accounts, the only thing is that I have him in my iCloud family for sharing photos and for tracking my location. He also wasnt even close, I was in South America and he in Europe. He was logged into iCloud via the website, and later I checked it on my iPhone and I could also erase etc via search my iPhone app. My question with this is if it is normal you can wipe someone else his iPhone/iPad? I think it would be better if you authorate someone to do that in case you lost your device.

That's not correct. You have to have the correct Apple ID password that is used for iCloud on that device:

Find My iPhone: Erase your device

Note: If you’re trying to erase a family member’s device, that person will need to enter his or her Apple ID password on this device.

You cannot use your Apple ID password to erase a family member's device. (Unless you and that family member happen to have identical passwords).