  At bottom, Theresa Wang with her daughter, Tian Tian, at home in Old Westbury, N.Y. Ms. Wang has decided the house is too large, and plans to move nearby. Top, Tina Wang and Andrew Wu of Daniel Gale Sotheby’s International Realty in Port Washington, N.Y., have the $3.68 million listing.   Credit Kathy Kmonicek for The New York Times     