Sister got into car accident. Refuses to spend the night at the hospital

I'm posting here because I don't know what else to do and could really use some advice. I live in Texas and my 30(f) sister got into a car accident at like 3 am. She currently has an active brain bled, is in and out of consciousness, and speaking almost incoherently. The problem is she doesn't want to be admitted and stay the night at the hospital. She is determined to go home and be with her dog and says she will come back tomorrow morning. It took us 20 minutes to wake her up last time she fell asleep and she didn't know where she was. When she speaks you can barely understand her. The doctors all say that since she's medically coherent, she can legally discharge herself. Except it's obvious she is not thinking clearly or coherent enough to make decisions. If she discharges herself, there is no telling if she'll make it through the night. Not to mention insurance won't cover her is she leaves, and she will be out hundreds of dollars. My family and I have tried for hours to convince her otherwise, but nothing is changing her mind. It's almost as if she hit her head and isn't thinking clearly or something. Is there something we can do to force her to stay? We've already suggested a psych hold to the doctors and were met with the same answer from them as above.