It's a clever and (to my knowledge) unique idea, but is it the best solution? Imprisoning the 'custodial' parent is always an option for a court when dealing with the flagrant disregard of a contact order, albeit an option of last resort, but one of the problems with it is: who will look after the children whilst that parent is in prison, where the non-custodial parent is not in a position to do so? The order made in this case does gets around that problem but, as Daniel says, it is still hardly likely to endear the father to his daughters, who will clearly blame him for their mother's imprisonment. As usual in such situations, there are no winners, only losers.
It is not clear from the report whether anything of this nature has already been tried, but surely the best option is to attempt to educate the mother, along the lines of our own contact activity directions? Of course, if that has already been tried and failed, then the court may have to do something more drastic. As Daniel also says, transfer of custody is another possibility, but the judge may not have considered it suitable here, in view of the mother having destroyed the children's relationship with the father. In which case prison may, after all, have been the only option.
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UPDATE: Much more detail about this case can be found here. As will be seen, "remedial intervention through counselling and parental training during the course of the trial was unsuccessful".