The regime's detention of a local politician in the powerful northern Buranupakorn family shows the coup-makers are targeting allies of their nemesis, Thaksin Shinawatra.
The North is a political stronghold of the Pheu Thai Party, which he backed, and the red-shirt movement which still supports him to this day.
The Buranupakorns held a grip on both money and the power in Thaksin's political network when he was prime minister, sources said.
Boonlert Buranupakorn, president of the Chiang Mai provincial administrative organisation, was suspended from his job without pay under a Section 44 order issued under the interim charter by Prime Minister Prayut Chan-o-cha.
- Earlier report: Family members escorted back to Chiang Mai
His niece, Tasanee Buranupakorn, was arrested over her alleged involvement in letters which allegedly distorted information regarding the draft charter that were discovered in Chiang Mai recently.
Mr Boonlert has also been detained in connection with the documents.
The Buranupakorn family has long been a powerhouse in Chiang Mai thanks to Mr Boonlert and his late brother Pakorn Buranupakorn's success in gaining influence over Chiang Mai's business and political circles, said sources.
They are among 11 siblings who came from a poor Chinese family that migrated from China to Chiang Mai.
When Pakorn's parents arrived in Chiang Mai they settled in a Chinese shrine community which is now an important business centre in the province.
The Buranupakorn family served as the political foundations of the former Thai Rak Thai Party, now the Pheu Thai Party.
The family also has close ties with Thaksin and the Shinawatra siblings.
Pakorn served as Thai Rak Thai's executive director and was a candidate for a cabinet post in the Yingluck Shinawatra administration before he died in 2013.
The Buranupakorn family's company and its affiliations run about 20 real estate development projects.
They also own several other businesses worth tens of billions of baht involving large hotels, golf courses, transport and exports.
When Chiang Mai received budgets for development in the past, the Buranupakorn family's businesses enjoyed benefits from various projects which the government funded there, according to the sources.
The projects dealt mainly with the real estate sector and infrastructure.
When Thaksin was in power, the Buranupakorn family and the Thaksin network were highly dependent on one another, said the sources.
"The Chiang Mai municipality office was used for meetings by those tambon and village leaders while planning Thai Rak Thai's election campaign strategies," said the sources.
Despite a slight hiccup in the Buranupakorn family's businesses following the power seizure by the National Council for Peace and Order (NCPO) in the 2014 coup, the family had never broken away from the Thaksin network that is led by Thaksin's sister Yaowapa Wongsawat and the red-shirt Rak Chiang Mai Group, said the sources.
The Buranupakorn family is now counting down to the day when the NCPO is gone and when it hopes to see the Thaksin network rise to power again, said the sources, though that may well depend on the shape of the next government.