Ordinary Love (2019) with Liam Neeson and Lesley Manville touches on this subtly. It’s about a long-married couple facing cancer, but the ghost of their deceased daughter hovers over every scene. The film implies that the "blended" dynamic is not just about new people; it’s about how existing family members blend their individual grief into a single livable day.
Similarly, Marriage Story (2019) flips the script. While not entirely about a "blended" family in the remarriage sense, its depiction of divorced parents (Adam Driver and Scarlett Johansson) introducing new partners shows the excruciating logistics of "sharing" a child. Neither new partner is a villain. They are supporting cast members in a tragedy where the only real villain is the failure of original love. By humanizing the "other" adults in the room, cinema validates the real-world experience of millions of step-parents: you are not a monster; you are a stranger learning a foreign language. Modern blended family narratives refuse to sugarcoat the child’s emotional landscape. Where old cinema might show children adjusting after a single montage of shared dinners, new cinema lingers on the wound.
The Half of It (2020) is a brilliant example. It is a Cyrano de Bergerac story for the modern age, but it features a single Chinese-American father and his daughter creating a family of choice with a jock and a closeted queer girl. The "blend" here isn't legal; it's emotional. The film argues that the most stable families are often the ones we build from scratch with other broken people.