The Tsedaka families of modern Samaritans claim descent from the tribe of Manasseh. The Bnei Menashe should be more closely related to them than to the other Samaritan lineages or to Jewish lineages.
They have oriental features, due to persecutory rapes while in China, but since Jewishness is determined matrilineally, that is irrelevant to the fact of their Jewishness. But after a couple of millennia of inbreeding amongst themselves, the Chinese Y chromosomes would be ubiquitous and queer any DNA tests. My guess.