Hello,
I'm working on groups sharing feature right now. It should be part of the next release 14.0, probably in next few weeks (it's not an easy thing to do, especially for single developer). Also it will be paid feature as I'm running out of money and donations won't even cover my running costs.

Part of the the Pro version will be also real-time synchronization so your changes will be applied to all your devices and shared users instantly.
All existing features will stay free.

Best regards,
Juraj Mäsiar