Three British sisters and their nine children split into two groups to cross into Syria, an Islamic State smuggler has claimed.
They passed over the border from Turkey earlier this week, the man told the BBC.
Khadija Dawood, 30, Sugra Dawood, 34, and Zohra Dawood, 33, and their children, aged between three and 15, sparked an international police search when they disappeared after travelling to Saudi Arabia.
The smuggler, identified as being in charge of some of IS's border operations, said the first group made the crossing early on Wednesday, followed by the second on Thursday.
Earlier this week, police disclosed that one of the sisters had made contact and there was an "indication" they may have already crossed into Syria.
The parents of the women have said they do not support their actions and pleaded with others not to make a similar journey.