Every year Google promote a Summit and each [mentoring] organization, in this case only NumFOCUS, may send two (2) members to the Mentor Summit.
NumFOCUS will nominate as Summit ambassador the lead administrator of the current year and the lead administrator of following year. If the current lead administrator are going to continue on that role on the following year then one of the other administrator can be invited by the lead administrator.
Any mentor interested to attend the Summit in case any of the administrators aren't able to attend the event can email at any time the lead administrator manifesting their interest. The lead administrator will select at his/her own discretion who will attend the Summit on his/her place.