Hi there Mrains925,
If you're not seeing all the people you want to add to a custom Photo Shuffle Lock Screen on your iPhone, let's start by making sure all the people you want to add are appearing in the People album in Photos.
To check, follow these steps:
1. Open the Photos app.
2. Tap the Albums tab.
3. Tap the People album.
Do you see all the people you've identified listed there? If you search for a specific name in the People album in Photos, does their specific album appear in your search results? Learn more here: Use the People album in Photos on your iPhone, iPad, or iPod touch - Apple Support
If you do see all the people you've identified in the People album there, let's make sure you're following the steps here to create the Photo Shuffle Lock Screen:
Add a photo to your Lock Screen
You can add a photo to your Lock Screen by selecting one from your photo library or letting iPhone intelligently suggest a photo that complements your other Lock Screen settings.
1. Touch and hold the Lock Screen until the Customize button appears at the bottom of the screen.
If the Customize button doesn’t appear, touch and hold the Lock Screen again, then enter your passcode.
2. Tap at the bottom of the screen, then choose one of the photo options (Photos or Photo Shuffle) at the top of the screen.
3. If you choose Photos and want to create a multilayered effect, tap at the bottom right, then choose Depth Effect.
Note: This option may not be available for all photos. Layering is not available on wallpapers with widgets. The multilayered effect is available on supported models. Layering is available only on images with people, pets, or the sky, and isn’t available on every image in those categories. Layering may not be available if the subject is too high, too low, or obscures too much of the clock.
4. To reposition your selected image, pinch open to zoom in on it, drag the image with two fingers to move it to the position you want, then pinch closed to zoom out.
You can also swipe left or right to try different photo styles that include color filters and fonts that complement each other.
5. If you choose Photo Shuffle, you can preview the photos by tapping , and set the shuffle frequency by tapping , then selecting an option below Shuffle Frequency.
You'll find these steps here: Personalize your iPhone Lock Screen - Apple Support
Take care!