Is it permissible, Islamically, for a father to bequeath a portion of his wealth to his only son and agricultural land to his daughters, knowing that the son helped his father accumulate this wealth?

If it is customary in a country for there to be leniency regarding financial matters between a man and his son who works with him, then the son is not entitled to any specific share of his father's wealth, and this is considered a donation from both parties. However, if it is customary to keep accounts, then the father is held accountable for what he spent on the son after the son reached maturity, and the son is held accountable for the wages of his labor, and the excess amount is awarded to whichever party is due it. If the son did not take possession of what his father gifted him during his father's lifetime, the gift becomes void, and the wealth becomes an inheritance, unless the custom of the country dictates compensating the son for his work with his father.