A pilot to deport failed asylum-seeking families without putting children in detention has seen just one leave the UK so far.
Some 113 families in north-west England and London were identified for the pilot by officials.
Under it, families are given notice to leave the UK, but allowed time to prepare without arrest or detention.
Ministers say they want to introduce a more efficient and humane system for removing those with no right to stay.
There has been widespread criticism over the years about detaining children in immigration removal centres while their families are facing deportation.
As part of alternative measures, officials are now considering placing families in monitored accommodation near to airports or splitting up parents.
Under the non-detention pilot scheme, immigration officers identified 113 families in north-west England and London, all of whom were judged to have exhausted their right to remain in the UK, to invite to special family conferences.
The meetings were used to explain to each family that they had to leave but would be given at least two weeks to put their affairs in order, with no plans to arrest or detain them.
The plan was to then set removal dates for those who still refused to board a flight voluntarily or take a resettlement package.
A Home Office presentation, written in October and seen by the BBC, conceded that there had been "no removals (yet) under these new processes" and that the family conferences had not been received positively.
Since then, one family has been successfully removed under the key limb of the test scheme, which entails giving them orders to depart on a given day.
The October document states that three families went on the run or cut contact with officials while others used the courts or appeals to halt removal.
Two families accepted resettlement packages, but another two who failed to comply were removed from the pilots, detained and then removed.
The documents also reveal officials are devising tougher measures called "ensured return" for those families who refuse to leave.
Under the proposed system, a high-level "removals panel" could impose sanctions including electronic tagging and "non-detained" accommodation near airports.
Another tactic being discussed would see one parent arrested or detained in order to force the other family members to board a flight.
Immigration Minister Damian Green said: "Significant progress has been made in working towards the commitment to end child detention for immigration purposes and we are currently piloting some proposed changes to our approach developed with partners.
"We have already announced that the family unit at Yarl's Wood Immigration Removal Centre will close."
Despite the difficulties with the pilots, the government has maintained the support of migration experts and charities who had been asked to help design the proposals.
But some say the government's asylum rethink has to go beyond dealing with just the final days before removal.
Penny Nichols, of the Children's Society, said evidence from abroad showed that most families voluntarily left if they believed they had received a fair hearing.
"If we don't have a system that is fair, we will have no opportunity to end detention of children for immigration purposes," she said.
She said a fair process involved people feeling they had had every opportunity to talk about their circumstances and to take responsibility for the safety and welfare of their families.
"There's lot of emphasis on removing people - let's have the emphasis on a fair process."