According to Fiqh i.e. jurisprudence, a boy has no need to acquire the consent of either of parents, so he can marry any girl even if it is against his parents' consent.
Please bear in mind that I'm not answering according to moral and sociological advice!
As for the second part of your question, we have nothing like that in Islam and as soon as a person dies his/her connection to their possessions is removed and the properties automatically go into the account of the heirs, so if one is going to deprive an heir of getting their properties, they must transfer whatever they have in their lifetime to other people.