Our iPad isn’t linked to my Apple ID, any way to locate? It’s lost

Here is Apple’s advice for lost or stolen devices:

If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

Use the Find My app to locate a lost or stolen device – Apple Support

If the iPad is not associated with your own AppleID, or if the Find My iPad feature was not enabled prior to it being “misplaced”, you’ll not be able to use technical means to locate it. 

The only way is to use find my for the account that's signed into it, if any.