Two lorry drivers have been charged with causing death by dangerous driving.
Three passengers, including a five-year-old girl, are fighting for their lives.
The bus was carrying a group of 11 passengers who were being driven to London to meet a coach which was taking them on a last minute holiday to France.
Three of the six men and two women who lost their lives in the pile-up have now been named Indian nationals who were working for Nottingham firm Capital One.
A spokesman for Wipro, the agency which had arranged the contracts, said: "It is with deep regret and sadness that we confirm the passing away of three of our colleagues, Karthikeyan Ramasubramaniyam Pugalur, Rishi Rajeev Kumar, and Vivek Bhaskaran in a tragic road accident in the UK."
Another employee, Mano Ranjan Panneerselvam, is one of those critically injured in hospital along with the five- year-old girl who is understood to be the daughter of one of the other passengers.
Panneerselvam's wife and mother are said by relatives to be the other women who were hospitalised, whilst three of his family members are understood to be among the dead.
Cyriac Joseph, the driver of the minbus who was born in India, was among those who lost their lives in the pile-up.
He had been hired to take the group from Nottingham to London when the crash happened near Newport Pagnell in Buckinghamshire in the early hours of Saturday morning.
Ryszard Masierak, 31, of Evesham, Worcestershire, is accused of eight counts of causing death by dangerous driving, four counts of causing serious injury by dangerous driving and eight counts of causing death by careless driving while over the prescribed alcohol limit.
David Wagstaff, 53, of Stoke-on-Trent, is charged with eight counts of causing death by dangerous driving and four counts of causing serious injury by dangerous driving.
Brett Smith, who passed the scene in a taxi before the emergency services arrived and stopped to help the little girl, said: "A family has been destroyed. I held a little girl by her arms, trapped inside a vehicle, for a good hour or so with the emergency services and the fire service trying to help.
"I walked home with a blanket that the ambulance service provided me to stay warm because the little girl has got my jacket to keep herself safe. The fire and ambulances services did a really good job."
Chief Inspector Henry Parsons, from the Joint Operations Unit for Roads Policing at Thames Valley Police, said: "Some of those involved were visiting the UK from India and we are working to keep families abroad informed."
Masierak was remanded in custody to appear before Milton Keynes Magistrates' Court today whilst Wagstaff was bailed to appear before the same court on September 11.