If any person is, by reason of minority, lunacy or other disability, incapable of making any declaration or performing any act required or permitted by this Act, then the guardian, curator or other legal representative (if any) of such person or, if there be none, any person appointed by the court upon application on behalf of the person under disability or on behalf of any other person interested in the making of such declaration or performing such act may make the declaration or a declaration as nearly corresponding thereto as circumstances permit, and perform the act in the name and on behalf of the person under disability, and all acts performed by such substitute shall, for the purposes of this Act, be as effectual as if performed by the person for whom he is substituted.