Dr Johnston said the incident "really put the wind up" Ms Pache who had been working for them for four months.
"You've got a young kid going to a foreign country ... she was absolutely terrified."
Ms Pache is now back in France.
She has not spoken to the ODT but did arrange a privacy waiver allowing Immigration New Zealand to respond to questions about her case.
Immigration New Zealand is part of the Ministry of Business, Innovation and Employment.
Dr Johnston, complained to the ministry about Ms Pache's treatment, explaining she was travelling with the family as a "companion" and "friend".
"I offered Manon either the week off in Australia or she could come to New Zealand with us as a friend, not working or getting paid. She chose to make the trip.
"My husband and I gifted the flight to her as she has been such a wonderful friend to our family."
Dr Johnston said Ms Pache occasionally looked after their daughters in Australia in the evening, "as a friend outside of work hours".
However, Dr Johnston maintained to the ministry and to the ODT that was not to be the case in Wanaka.
Dr Johnston said she explained that to a Queenstown immigration officer while Ms Manon was being held.
"[The officer] asked if Manon was working whilst here and I said 'definitely not'.
"I own a veterinary business in Australia and work 12 to 14-hour days and this was my holiday to spend time with the kids.
"I also explained that the kids' grandparents were with us too.
"He asked what would happen if the four Johnstons wanted to go out to dinner. Who would look after the children?
"I said the children would be coming with us; that is the point of a family holiday.
"He then said: 'Well Manon's lying, because she told me she might look after the children if you went out to dinner'."
"I explained again that this was our family holiday to spend with the kids."
Dr Johnston said Ms Pache called her from the police station late in the afternoon "in great distress".
She was "not even allowed" to phone the French embassy or access her belongings.
Dr Johnston said she had been willing to sign a statutory declaration stating Ms Pache was with the family "for holiday reasons only", and she would have participated in an interview but was not given the opportunity.
She described [the officer] as "incredibly rude and unreasonable" to both Ms Pache and herself.
"I believe the visa refusal decision was not made justly and the treatment she received from the immigration officer was unprofessional and intimidating."
Responding to Dr Johnston's complaint, border manager, border operations, Immigration New Zealand Amanda Mehrtens said initial conversations "led to concerns she may not be a bona fide visitor".
"The border officer explained that for immigration purposes, work is defined as any activity undertaken for gain or reward."
"Given that Miss Pache's accommodation and travel had been provided to her in exchange for undertaking child care activities this would constitute work.
"As such, Miss Pache was assessed as likely to breach any visitor visa granted to her.
"Visitors may not work while on a visitor visa."
Ms Mehrtens said the interview recording showed the officer was "polite and did not act in a manner which I consider unreasonable".
Responding to emailed questions from the ODT, Immigration NZ national manager border Senta Jehle said Ms Pache was refused entry "on the grounds that the arrangement she had made with the Johnston family constituted work and as such would be in breach of any visitor visa granted to her".
Ms Jehle said it was unfortunate there were no facilities at Queenstown other than police cells in which to accommodate passengers overnight and that was being looked into.
Ms Jehle did not respond to ODT questions about the harm Ms Pache's visit might do and whether or not immigration officials had room for discretion.