Oliver, I think this is your area... According to Ethnologue, Dinka [1] is a Nilo-Saharan "macrolanguage", with languages Northeastern Dinka [2], Northwestern Dinka [3], South Central Dinka [4], Southeastern Dinka [5] and Southwestern Dinka [6].
The whole population is 1.4 million, it's about very poor South Sudan. Is there a sense to create one Wikipedia or to go with separate languages?
[1] https://www.ethnologue.com/language/din [2] https://www.ethnologue.com/language/dip [3] https://www.ethnologue.com/language/diw [4] https://www.ethnologue.com/language/dib [5] https://www.ethnologue.com/language/dks