My name is Megan, I'm the head of customer support at Location Labs/Safely.
After registration, any compatible Sprint or Nextel handset that you would like to locate (up to 4 phones) can be added by following these steps:
-Log into your SFL account.
-Click on 'Manage Account' at the top right of the page.
-Click on 'Add a Family Member'.
-Follow the rest of the steps.
(It's important to note, though, that currently, locating your new Apple iPhone using Sprint Family Locator may result in larger possible locate areas than other phones. We're working with Sprint and Apple on addressing the issue and will provide updates as soon as we have new information.
If you are looking to track your iPhone, there are other options. You can use iCloud to track your iPhone for free. You would need to set up iCloud in your iPhone through the settings. Once it has been set up on your iPhone, you can log onto www.icloud.com to track your device. Hope this was helpful!