A rebel faction has split away from the main group.

一帮反叛者从核心组织中分裂了出去。

《牛津词典》

It means you cannot tell they're members, unless they're members of the main group.

只是表明您不能说明它们是成员，除非它们是主组的成员。

youdao

Otherwise, you may add someone to the main group who's already in a breakout subgroup.

否则，可能会将断接子组中已经存在的某人添加到主组中。

youdao

In September,a power struggle erupted in violence in the lower Juba region between al-Shabab and Hizbul Islam, a clan-based Islamist-nationalist group which had been al-Shabab's main ally in its year-long battle to overthrow the U.N.-backed government in Mogadishu.

VOA: standard.2010.01.02

Likewise the worry that the main pro-independence group, Fretilin, has leftish views.

ECONOMIST: Let East Timor vote

Further proof came in another story making waves in Strasbourg, the departure of British Conservatives from the main centre-right group, the European People's Party (EPP).

ECONOMIST: Charlemagne

Modeled deliberately on the American-Israel Public Affairs Committee (AIPAC), the main pro-Israel lobbying group, the CANF changed American policy toward Cuba.

CENTERFORSECURITYPOLICY: The Man Who Lived to Save Cuba