Try CAIEngine and stiDbItems:
stiEngine = catia.GetItem("CAIEngine")
# The GetStiDBItemFromAnyObject() needs a document object as parameter.
stiDbItem = stiEngine.GetStiDBItemFromAnyObject(product.ReferenceProduct.Parent)
stiChildren = stiDbItem.GetChildren()
for i in xrange(1, stiChildren.Count + 1):
fullPath = stiChildren.Item(i).GetDocumentFullPath()
Good luck