My wife and I are non-US citizens living abroad so we are not entitled to enroll in obamacare.
However we would like to insure our 7 year old US citizen daughter, who lives abroad with us. However the enrollment system force to add at least one adult, and only then add children. (We tried Massachusetts).
Is there a way to enroll only our 7 year old US citizen child?
You can get coverage through CHIP, the Children's Health Insurance Program. CHIP offers free-or-low-cost child-only coverage.
However, since CHIP is state-based program there may be some residency requirements. If you are abroad all year then CHIP won't do much good as the network will be primarily state-based US care providers.