Currently the way to share the app with a partner so multiple people can log data across devices is to log in with your account on your husband/wife/partner's phone. Then the app will synchronize across devices, as long as both devices are connected to the Internet.
This will work best if each device has an up-to-date version of the app installed. App versions running on unsupported Android or Apple OS versions may not sync as expected. A phone that's in low-power mode or with "Background App Refresh" turned off may also prevent the app from synchronizing.