Hi Tyssiag ,
Yes , I think you are correct , some descendants used their mothers surname as also their surname .
Telesia Falelavaki , I think married Kinau Paino Gatuhau.
I think they had one son named Pelenatino Gatuhau (Falelavaki) and he married Maleta.
They had one daughter by the name of Filomena Gatuhau (Falelavaki)who married Arthur Elbourne.
They had children in Fiji : Fred Elbourne , Simon Elbourne and others in Fiji.
I am a 3rd generation descendant of Palatino Pipisega Falelavaki (younger brother of Telesia Falelavaki)
you could email me directly at firstname.lastname@example.org