I don’t know what the coaches’ contracts say about what can or can’t be done with the singers during that time, but apparently Ariana Grande doesn’t really care too much.
In fact, as the coaches often present their new team members with a gift, such as a jacket or a bobblehead, Grande gave out health kits that included items like tea and honey to help with vocal longevity.
Kelly Clarkson noted that Grande was always sending things to the hotel for her team members, and Grande has said more than once in just the first couple of episodes that she cares about the singers outside of the confines of the competition.
Ariana Grande Secretly DMs Her Team On 'The Voice'