I've just looked at your db. Do you realise what you are asking will make your highlighting inconsitent?
To make things clearer, just put the layout in Excel with the correct shading and the grouping and upload it here.
Also, what about removing (i.e. setting it to White) the Alternate Back Color in the Detail section?
I attached a jpeg showing what i would like to achieve, but for now i took your advise and removed the alternate back color. thanks