Considering their age structure, I have looked through the apple app store found that the Kid’s category are separated into under 5, 6-8, and 9-11 years old group, as the first thought is presenting this with an app. In this case, under the research, I have found out that for under 5 is most likely to have pure story book apps and then over this age is likely have more games than storytelling but Disney own’s apps have a Frozen story book which includes little interactive parts that they can play with.
Nosy Crow & Disney Series
There is more immersive playing and learning for older children.
FriendStrip App
I have had a go to play a bit, it gives you several story board and you can select the one you want to do and then just pretend you are the main character and act with it. I had lots of fun picturing. 
Even though this age stage of children no longer fancy fairy tells that much but they do need to read. So that, I have browse through websites, looking for those books which are suitable for 6-8 children.
http://www.booktrust.org.uk/books/children/booklists/242/
Thus, according to their suggestions and my research, I have revised my initial project idea a bit.
The modified intended idea/concept of the project:
This is a project mainly for children, especially those who are at their younger stages, age are around about 6-8 years old. The app would be an interactive Augment reality story games, for which the character are all 3D modelled and children can chose which character she/he wants to be and by sending 360 their facial image to the app, it will end up like you in the 3D modelled story, and there is more game could interact with.
Still finding the books, which I could use, as I wish to produce a series of it.
Rationale is key alongside realistic expectations on delivery, some of the features described such as facial mapping over a 3D character would be possible but not necessarily possible given the time available to yourselves. The AR route is a solid route to follow and could be packaged nicely alongside story materials and brand identity.
I am aiming to run a AR workshop (how to make a bespoke AR application) early in the new year or before Christmas (time permitting) as you could make your own AR application very simply. Consider potential issues with the technology also such as tracking reliability, environmental conflict (i.e. lighting conditions, camera quality e.t.c)