Ok this post does not make sense to me, what are the orgininal Lakota Bands? Are you talking about the Dakota? Which are the orgininal people? As far as I know the Caddo are not related to the Lakota. They could have been related to the Dakota way back around 900 but there is no current relationship and The Lakota did nor separate from the Dakota until they were in Michigan
A very interesting question! A Siouan speaking tribe, the Biloxi, resided in Louisiana when the Lakȟóta were migrating to the Plains from the southeast, around the present day Virginias. The Biloxi language is related to Lakȟóta and it has words, for example, that have the same meaning as those found in Hidatsa -- another Siouan language that is currently found in North Dakota. So, it seems reasonable to assume that there may have been a prehistorical relationship that existed between the Caddo and other Siouan tribes in that region. As of two years ago, a "Siouan and Caddoan Languages and Linguistics Conference" was still being held. It seems that this particular group might of help to provide useful information.