Cesc Gay’s “The People Upstairs” (a.k.a. “Sentimental”), Nacho Álvarez’s feature debut “My Heart Goes Boom! (“Explota Explota”) and the series “Ines of My Soul” (“Inés del alma mía”), based on the book of the same name by Isabel Allende, will have their world premieres at the San Sebastian film festival in September.