I'm adding only one point, that for me is the key issue, from an American point of view, though it might have no importance from your own or her own points of view. Apparently her family wants to control what sort of a person she can marry, and presumably wants to keep her close to home and close to them. This is true for daughters far more than for sons, and in the majority of cultures and countries around the world. But there are daughters, as well as sons that set themselves free from such family containment, because love and/or often career draws a daughter to NOT emulate the life choices of other females in her mother's generation, to in effect, Outgrow her mother's degrees of freedom.
Families rarely accept such choices by a daughter, and few daughters will dare the disappointment, disapproval and partial or total ostracism that's likely to follow on a choice to leave the narrow orbits allowed to females in their families. But some do, perhaps because there is an inborn need to extend their personalities beyond the limits that have constrained their families before. All those women who went with their men or without a man across the ocean to the New World had to leave their families behind. They all suffered from the separation of mother and daughter. And many many daughters have also chosen the man they loved over the closeness of mother and family, or tried to split the difference, as is the outcome in the Greek myth of Hades and Persephone.
If a woman chooses to find her own identity separate from what has been assigned to her by her family, she is quite likely to disappoint her mother and violate the boundaries of her family's traditional rules. What she loses in instinctual, unconscious relatedness to her family (which is substantial), she can gain in consciousness of the breadth and depth of human nature and possibilities and of the meanings of life and of development toward her own unique individuality in relation to the whole of the cosmos and of something greater than herself.
It sounds like you don't think you have a right to "kidnap" her heart and soul against her parents' wishes to be your bride and to follow a less limited path together with you. But it boils down to HER wishes: whether she wants to endure her family's disapproval for some period of time or not. Even that disapproval will only last until the family, or some of its members decide that she's more important to them as an individual following her own desires than maintaining the family traditions and the approval of those who'd prefer to ostracize her. Perhaps you've never heard that there's a natural tug of war between a daughter's mother and her lover, and she has to decide at some point in her life which she will prioritize over the other. Your beloved might have reached that age, where she was aware somewhere inside, consciously or not, that it was time for her to make her own choices independently of what her mother and father wanted. OR she was still absolutely blindly obedient to what her family dictated as her limits and equally blind to the fact that her obedience was crippling your need to build a future with only her desires and yours as top priorities, so her parents' interference was an unacceptable hindrance.
Sicilian tradition acknowledges the absolute dictatorship of a father over his daughter's doings, but integrates the shift of authority from father to husband by arranging for the prospective husband to "kidnap" the daughter from her father's house as a way of symbolizing the transfer of power from father to husband.
Perhaps you're not getting cooperation from her family because you've not made it clear to them that you are Marrying their daughter and therefore taking responsibility for her life and future onto yourself. It's even more common in Europe than America for couples to live together and even have children without legally marrying, and that makes the traditional attitudes toward belonging and responsibility much less clear. Perhaps it's that level of commitment to an enduring future that would clarify the choices for both your beloved and her family. Then if she said YES she wants to spend the rest of her life with you and her family said NO, that's now what we want our daughter to do, you would then be in a moral position to prefer her wishes and yours over theirs, and argue at her side that she deserves to choose her own happiness over their tradition.
Of course in America our values are slanted more towards change and individual initiative and less towards maintaining traditions than they are in Europe. This, at any rate, is an American perspective on the issues you are dealing with. When you are desiring more Freedom from her parents to build a life with her, you need to be offering more Responsibility for both her and yourself as the natural condition of such freedom.