What is the ruling of Islamic law on a sister gifting her possessions to her brothers, and is it just for her brothers to inherit what remains of her property instead of her daughters and husband?

Your statement: "I find it unjust for my siblings to inherit the other part of my property" is incorrect, for your siblings inherit according to Allah's law. A gift (hiba) is permissible, but it is not allowed if its intention is to deprive heirs; in such a case, it is considered a major sin. If the gift is free from this intention, then it is permissible to transfer your ownership to your wife and daughters, provided they take lawful possession of it, dispose of it as owners would, and that you are just among your daughters. However, if the gift is conditional upon your death, then it is a will, and a will to an heir is not permissible, based on the saying of the Prophet (peace be blessings be upon him): "Indeed, Allah has given every rightful person his right, so there is no will for an heir." Remember that giving a gift to siblings involves maintaining ties and showing mercy, and lifetimes are in Allah's hands. Your siblings may benefit your daughters after your death, as Allah Almighty says: "Your fathers and your sons – you know not which of them are nearer to you in benefit. [This is] an obligation from Allah. Indeed, Allah is ever Knowing and Wise."