The Bradford sisters missing with their nine children were stopped from leaving the UK in March, ITV News has learned.
Their trip to Saudi Arabia was rebooked for May but there is no suggestion they were intending to travel to Syria at that time. Police are now trying to work out when the trip was planned.
The fathers of nine missing children from Bradford fear they have been taken to Syria where a relative is fighting for an extremist group, their solicitors have said.
Balaal Khan, acting for the family, said the men are "distraught and feel helpless" and are concerned their children's lives are "in danger".
It is believed at least ten of the 12 family members boarded a flight from Medina to Istanbul in Turkey - a commonly used route into Syria.
Mr Khan said it is understood the sisters have a relative fighting for either Islamic State or another extremist group in Syria, and it is feared they have met up with him.
Speaking from Pakistan, one of the husbands of the missing Bradford thought to be heading to Syria has told ITV News of his worry.
Here's what we know about the Bradford family of 12 who are feared to be travelling to Syria.