In order to help a child without decreasing his/her share of the inheritance, you would need to make a gift separate from his/her share of the inheritance or draw up a will that makes a bequest separate from his/her share of the inheritance. In that way, the gift will not reduce his share of the inheritance, on the contrary it will add to it. When making the gift, it is important to specify in the legal document that the gift is separate from the heir’s share of the inheritance, otherwise it will be considered an advance payment on his/her share of the inheritance. In order to avoid any subsequent legal challenges, the gifted amount should not exceed your disposable portion. To forestall any problems, consult your notary.