Living in Two States, What do I Do about Switching Plans After Accident?

My brother was in a terrible car accident in New York two weeks ago. He has an Anthem/Obamacare policy from the New Hampshire heath exchange. He also has an apartment and a business in New York. He would like to do his rehab in New York (for a lot of reasons). The New Hampshire policy will not cover rehab in New York. Anthem suggested that he apply for Obama Care on the New York exchange because it is the open enrollment period. He did, but he is worried that he cannot really have two subsidized plans and so one or the other, or both may be deemed invalid. He is also worried that if he switches plans while in the midst of an ongoing injury coverage may somehow be denied. Can you help?

Also, if he gets a New York Obama Care policy, he will not be covered under that policy until March 1st. He has a final surgery on Friday and then Anthem wants to transport him 8 hours in an ambulance to New Hampshire to begin Acute rehab. He would prefer to just stay at the hospital he was air lifted to and begin acute rehab there and then be transported an hour to a subacute rehab facility near his home in Rochester New York. How do we go about getting the right coverage to make this happen? Are there things we should avoid doing?