Based on reports, the Kingdom is also not in favor of the ways of Negan and his Saviors so it would seem like Carol and Morgan might draw some help or assistance from them to be able to help their colleagues from Negan.
However, based on the statements of Negan during the Season 6 finale before he pummeled his victim to a pulp, he does not intend to kill all of the members of Rick’s group from Alexandria but just wanted to send a message to them.
He also said that it is also one way of avenging the death of many Saviors in the hands of Rick’s group when they took over a facility that was previously occupied by Saviors.
He said that he just wanted Alexandria to serve him and the Saviors the way Gregory and the people of Hilltop were doing. Negan said that Rick and company would be of no use to him and his Saviors if they were all dead.
Thus, Rick and company shall not need any help at all from anybody to escape Negan because they would be free to go once he is done with his first victim. They would just need to offer him and the Saviors something in return for keeping them alive.