Apple's fingerprint system Touch ID will store up to 10 individual fingerprints. You can add up to 9 more fingers after the initial setup by following these steps:
- Open the Settings app on your iPhone or iPad.
- Select Touch ID & Passcode.
- Enter your Passcode.
- Tap Add a Fingerprint and follow the prompts.
Adding an at least two fingers to your Touch ID database makes unlocking your device and using Apple Pay much easier. It is recommended that you add at least your thumb and pointer finger so you can access your Touch ID sensor while holding your device with different grips and in different orientations.