Let`s write it all down in this topic, so anyone can do his research when having a trouble.
You can only add one camera to the dashboard. After touching the icon only one camera will appear. However on the top right corner of the dashboard You will find icon for outdoor station preview. If You click this icon, You will be able to toggle between all added cameras.
In ABB/Busch free@home You cannot manage the size of camera icon on the dash, it`s only a KNX feature.
Try to add IP cam as a default outdoor station cam, that`s a pretty fun feature.