I am sorry to tell you that there is not much your friend can do. Under French law, a Will is not essential. When someone dies in France, all the heirs (and you are right that children are entitled to a statutory share of the inheritance, even when there is a Will, and even against a Will) are by law given a term in which to either accept, accept under inventory, or renounce the estate. This is done in France, at a notary or at the Tribunal de Grande Instance of the last habitual residence of the deceased. This term is 10 years. If a person did not ask a notary or the TGI to be put into possession of his/her share of the estate, nor renounced it, within this 10 years' time, then they are considered as having renounced it by the law (specifically art. 780 of the French Civil Code).
The exceptions to this rule are as follows, and if your friend falls into one, then she may go to either a notary or the TGI to ask for her share of the succession:
1. If she did not find out about the death for legitimate reasons (i.e. she was isolated, the death was not reported, it happened somewhere very remote etc.), then the 10 years commence when she did find out. If the 10 years have not yet expired (i.e. if she found out in 2006), then upon proof she may go to a notary to claim her share;
2. If she, in fact, at the time of death, either directly or through her mother, accepted the succession. The fact that her mother received insurance money is not indicative, because insurance is paid not as a heritage, but as a direct right of the insurance payee. However, it does indicate that the mother was in contact with France and maybe she did do the right paperwork at the time, in the name of her daughter, if she was a minor. To find this out, it is best to inquire with a French Notary. The French notaries (any of them will do for this procedure) have a central national Register of Successions, which includes any authentic wills, and any declarations of accepting the succession. She may find out whether one was made in her name, or at least who was considered legally the heir.
I hope my answer was useful and look forward to your rating, which is essential to my activity.
Dr I L Vlad