Saving songs to apple music liberary using iphone 6

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We are a family of 4 and use a familiy account apple music with me as administrator.
Everything works great when we use our apple id's except for my daugher. She have made some playlists and saved some songs to the differents lists and is just in the beginning and now she meets problems. She has estimated 10-15 songs in each playlists but when she added new songs to the playlist it didnt synch and dissapeard after some time. However we have not had those problems ourself. Do anyone have a solution to the sync problem and why the recently added files dont save, but dissapear after some time? She has also avtivated the icloud music liberary and has tried to log of an on again but the issue is still there.