You can turn on screenshots for an Apple Watch that you’ve set up for a family member: Here’s how:
° Open the Settings app on your family member’s Apple Watch.
° Tap General, then tap Screenshots.
° Turn on Enable Screenshots.
When your family member takes a screenshot on their Apple Watch, the screenshot is sent to your iPhone. To view the screenshot, follow these steps:
° Open the Watch app on your iPhone.
° Tap All Watches, tap your family member’s Apple Watch, then tap Done.
° Tap General, then tap Diagnostic Logs.
° Tap a screenshot to view it. To save or share the screenshot, tap the Share button, then choose a way to share.
(This how-to is based on my experiences and info on Apple’s support pages — where the images sometimes come from.)