Have you seen this? - http://answers.unity3d.com/questions/165513/importing-sketchup-colladadae-into-unity.html

* this is a good question for Unity Answers as well

That sounds good, I am not sure exactly how to that but its something I did not think or was aware of, thank you. 

If you have multiple models a/o complex models, it will be a good idea to parent them with a GameObject, and to make that GameObject a child of the ImageTarget - so the GO is the direct child of the IT. This helps to avoid certain problems that you can encounter when transforming a model to the local scale of the IT.

If you have a lot of models, you may be able to accomplish this programmatically at runtime, rather than in the Editor. But with this approach, you'll need some way to define the relative positions of the models to each other.

Can you post or PM a picture of your 3D scene?

That was my first port of call. But thank you. I think the problem is that I am unable to make my model a child of the image target as there are many different small models that make up the full scene. I am now trying to export the model (maybe as collada) and bring it back in as one.

Would anyone know if this is possible?  

Have you seen this tutorial? - https://developer.vuforia.com/resources/tutorials/image-targets-unity