When enrolling in Family Sharing, each invited member can choose whether or not to allow tracking of their location; tapping Not Now defers the decision, and it can be changed later.
Apple grafted Family Sharing into iOS 8 so that it's available almost as a special group relative to Find My Friends. You use Find My Friends to see family members, and they're listed under a Family heading in the Share My Location options in Settings. As with Find My Friends, you can disable all location sharing or pick individuals and remove their ability to track you.
If you remove a family member, you can invite them back later, and they can confirm that they want to follow your position.
Family Sharing members can also use Find My iPhone for tracking as long as sharing is on, seeing where all devices that are both associated with an included iCloud account are located and have location sharing enabled. (When location sharing is off on a device, its online or offline status remains revealed, and it can be forced to play a sound. With the Apple ID password for the account, it can also be put into Lost Mode.)
What it's good for: time-limited sharing of your location with one or more people.
iOS 8 baffled a number of people, if Apple's and other discussion boards are any indication, by moving temporary location sharing groups from Find My Friends into iMessage. (Apple's support note on Find My Friends remains out of date as well.)
With any individual or group iMessage, whether already underway or one you're starting by selecting a member or members, you can access sharing options by tapping the Details button to the right of the person or list of people's name.
You may tap Send My Current Location to push a map slice to them of your whereabouts. If that map is tapping in Messages, it opens a Maps view within the Messages app. You can also tap Stop Sharing My Location, which turns off location sharing just as if you tapped in the Settings app.
For individuals or groups that you're not already connected with, you can also tap Share My Location and choose among sharing for an hour, until the end of the day, or indefinitely. The last of those options is equivalent to adding someone to Find My Friends.
Apple says you may have up to 50 temporary groups with up to 50 people in each group.
What it's good for: sending a static map, rather than enabling real-time tracking.
The last of these options is the simplest. Rather than send dynamic location information, you can share a map tile from the Maps app by tapping the Share button, and then choose a means of sending it.
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