Preserve group shopping items, don't merge with default list

When I add account on a phone and start syncing from my group (my shopping items entered on the web site or on another phone), the default shopping items stay. This makes my list on a device merge with the group. So every time I add a device to a group I need to clean the list of available items. 

Would you be able to ask me when I join a new device if I want to use cloud items or merge with those on the device?