Marla McCants, who is one of the most successful patients to come out of My 600-lb Life, was aided entirely by her daughter Sierra McCants throughout her life. Though My 600-lb Life is typically focused on Dr. Younan Nowzaradan, AKA Dr. Now's, patients who are in desperate need of help with their health, the families surrounding the patients are often featured in episodes of the series. Sierra was shown throughout Marla's episode as a supportive daughter who wanted the best for her mother, but she was having a tough time being patient with Marla after her surgery. Sierra, one of Marla's three children, had taken on helping her mother with everything.
https://screenrant.com/marla-mccant-daughter-sierra-600-lb-life-season-3-update/