that is sad you have separated them. They really do need each other. They will grow up with your birds and like you said sound the alarm but to separate them is cruel.All your birds will be running together right? so let the goslings grow up together too along with your chickens.
https://www.backyardchickens.com/threads/reasons-why-you-shouldnt-keep-just-one-goose.1220102/
https://www.backyardchickens.com/threads/reasons-why-you-shouldnt-keep-just-one-goose.1220102/