Its two branches, Ramu and Lower Sepik, had belonged to Donald Laycock's now-defunct 1973 Sepik–Ramu proposal.
The Ramu-Lower Sepik family is not accepted by Søren Wichmann (2013), who splits it into 4-5 separate groups.
[4] Foley (2018) accepts that Ramu and Lower Sepik are related on the basis of morphological evidence, although they are typologically still very different from each other.
Foley was able to connect them lexically, but the primary evidence for a Ramu – Lower Sepik family is a number of irregular plural markers shared by the Lower Sepik languages and the Ramu languages Watam and Bosman.
[1] Reconstructions of proto-Lower Sepik and proto-Ottilien (proto-Watam-Awar-Gamay, a Lower Ramu branch) from Foley (2005) are as follows.