My sister and I both use a Sony Xperia. I am looking for a free app that can tell me the location where my mom, dad, or sister is.
Does such an app exist?
Glympse is an app which does just this.
Working on Android, iOS and Windows phones, you can allow another person to see your location for a defined duration.
The app sends a URL to the other person which will show your position on a map. This can also be used on a PC in a browser. The URL will expire after the defined time to protect privacy.
Family Tracker: Locate Phones - Has ability to send a Stealth Ping, which forces an automatic location update of the remote device without the person being notified. BUT they have to have GPS on for you to receive location and has to have app installed. Once you installed APP asks you for the email of the person you want to track.
I have installed Locate Family and it works great, you need to invite other person to install the APP and when other persons Location/GPS is turned on you will know where it is.
The Google+ app has location sharing which works reasonably well for this:
You'll see the people around you who are sharing their location with you. You'll probably need to add your family using the "person list" icon in the middle-bottom of the screen and selecting "Invite more people."