Didn't one of the episodes indicate that Chelsea was on Medicare or Medicaid? I thought I remembered a conversation about that here and how irritating it was that someone who was basically being treated to her own house and expenses by her father without being required to get a job or even finish high school in return could be covered by programs meant to help people of limited means. I think this came up last season, when she had the first knee operation.
I think Chelsea may have aged out of her parents' health insurance already. Doesn't that happen at eighteen unless the child in question is enrolled in post-secondary education of some kind?