In this section, “instrument” means a deed, grant, or other written instrument other than a will as defined in § 4-414 of the Estates and Trusts Article. This section does not limit the right of an individual to provide for distribution of property by will. Unless an instrument executed on or after June 1, 1947, clearly indicates otherwise, “child”, “descendant”, “heir”, “issue”, or any equivalent term in the instrument includes an adoptee whether the instrument was executed before or after a court entered an order for adoption. Unless an instrument executed on or before May 31, 1947, clearly indicates otherwise, “child”, “descendant”, “heir”, “issue”, or any equivalent term in the instrument includes an adoptee if, on or after January 1, 1945, a court entered an interlocutory order for adoption or, if none, a final order for adoption.