Petra Ecclestone, the fashion designer/socialite, has filed legal docs to change the names of her 3 kids -- from her ex-husband's name to hers ... and it underscores the bitterness of their divorce.
According to the docs, obtained by TMZ, Petra wants the last name of her three kids -- Andrew Kulbir Stunt, James Robert Frederick Stunt and Lavinia Stunt, to Ecclestone.
As for why, according to the docs, "To conform children's last name to mother's last name ... difficult in both daily life and traveling with children with a different name to mother."
The doc goes on to give another reason for the name change ... "Change and remove last name of absentee father who is subject to regular negative media and tabloid articles and criminal investigation."
The father of the 3 kids, James Stunt, is awaiting trial for money laundering, forgery and racially abusing a black police officer ... charges he has denied.