Hi W.,
You probably won't think this will work, but it did for us. When we first moved to our house several years ago, my daughter felt uneasy about sleeping in her own room. Being in a new house, I also felt more safe with both my son and daughter in our bed. Well, that didn't last too long because we were ready for some alone time. It took a little while, but after a few nights of my daughter coming back and forth, we figured out a solution. My son, luckily, never gave us any issues. We would put her to sleep around 8pm (they have always had early bedtimes). She would just sorta lay there for a while, but I would assure her that I would be in to check on her several times. In the beginning, I would leave her TV on, or you can turn on a radio. I would make sure that she would feel me touch her arm or kiss her forehead the first couple of times I checked on her. This just let's her know that you are keeping your end of the bargain and let's her feel safe to doze off. I would still come in to check on her after I knew she was asleep because there were times that she would wake up. If she feels you still coming in, she knows that you are still keeping your word. Then by the time I went to bed, I would make one last check. Yes, she would still get up here and there during the night and slip on over, but I would find the engery to get up and walk her back and tuck her in. I would just wait a couple of minutes until she was asleep again. Just like anything else, they need to find this as a habit. It will not work the first night, but rest assured, it will not last too long. Once she understands and KNOWS that sleeping in her own room is okay, she will do it without hesitation.
ALSO, there will be nights that she does have a nightmare or feel uneasy during those stormy nights. Of course, allow her to sleep with you after a nightmare, if she chooses to. But, give her the option to go back to her room. During stormy nights, last night being one of them, would wake up in the middle of the night from the storm and carry my kids to my bed (my husband works nights). Then when they wake up, they are surprised to see that they slept in my bed. It's amazing what kind of a good mood they have after knowing that they slept safely with mom that night. I have to take advantage of this time because my kids are now 9 and 10 and there will come a day that they will not think that sleeping with mom was "cool".
Since my "cool" days are limited, I will continue to bring them to my bed during a stormy night and surprise them with McDonald's during lunch until Mom is no longer "cool". They are still my babies after all, but that is another post:)
Good luck!