UKM / Romein / Commonwealth

Hi all

In light of the Romein decision, I’ve been considering UKM eligibility for myself and my sister but have become a bit tangled up some of the finer detail. Apologies for my ignorance, but on a quick reading, my situation appears similar to Romein, however I’m unclear what impact my/my Mother’s Commonwealth country of birth has - does this disqualify us from UKM? Some of the media soon after the Romein decision suggests that the decision only opens a route for those born in non-Commonwealth countries.

Note: We realise we have a visa route through Ancestry, but for the purposes of this post, I’m specifically interested in the possibility of Citizenship via UKM.

Sister/me: both born in NZ prior to 1983
Mother: Born in NZ mid-1950s, British Citizen by descent
Mother’s parents / my Grandparents: Both UK born (Grandfather in 1922), migrated to NZ as adults.

I don’t know a lot about the process my Mother went through to gain her UK citizenship, but I know she held it prior to the birth of my sister and I, as I have sighted her UK passports covering those years which note her status as a British Citizen.

Any clarification on the Commonwealth issue or suggestions of where I might find clarification most appreciated - we’ve not found the HO guide particularly helpful. Thanks!