Dear mustluvpips14 - Unless there is a legal guardianship he can do what he pleases including get married. If they will not let him out of the house they are committing a crime of kidnapping or false imprisonment and the police should be called. Anyone over 18 is an adult and free to go where they please. The parents have no right to do what they are doing and the authorities should be contacted.
This is similar to a power of attorney but it is done through the probate court and essentially gives the guardian the complete power over the individual much like that of a parent. It mist be obtained through the court.
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