Absolutely! With Family Sharing on the App Store and Family Groups on Google Play, each child in the family can have their very own Club Penguin Island membership!
Check out the following links to Apple and Google support for more info:
- Setting up Family Sharing (App Store): https://support.apple.com/en-us/HT201060
- Setting up Family Groups (Google Play): https://support.google.com/googleplay/answer/7007852?hl=en&ref_topic=6209538
NOTE: These features may be subject to availability in your region. Please check with Apple or Google support.
For information on purchasing membership via the website, please see How do I purchase membership for Club Penguin Island?