Rebecca Chalmers is a former resident of Elm Tree House I.
Rebecca was quite a sneaky and devious person in the Dumping Ground. She had a strong rivalry with Justine Littlewood, and hated the fact that she had to share her room with her when she came back to the Dumping Ground. She also had a crush on Crash Daniels, which aggravated her rivalry with Justine even more been as Crash and Justine became quite close friends in the last series. Rebecca hates her name being shortened as a nickname, which Justine takes advantage of and calls her "Becky" or "Becks" cos she knows it annoys her.
Before living in care, Rebecca used to live with her father, step-mother and younger step-brother, Jake. He father and step-mother would usually leave Rebecca on her own to look after step-brother Jake (who was just a toddler), and they'd usually be out for hours until late in the night. It's unknown how Rebecca got into the care system, but she ended up being placed into Elm Tree House. It's safe to assume she didn't have a good relationship with her step-mother. Rebecca's past was revealed slightly in the episode, "Toddler in Town", when a toddler was left on the Dumping Ground doorstep. Charlie reminded Rebecca of Jake, and he also reminded Justine of her younger step-brother Billy. Which helped Justine and Rebecca bond a little, as they had something in common.