Children and sleeping?

My fiance's child used to go to sleep in her bed no problem when she was younger now that she is getting older she is wanting to sleep with us more. That being said she fies fine falling asleep in our bed and us putting her in her bed even when she wakes up to go to the bathroom she goes back to bed. She just doesnt like being alone when going to sleep. Its not an issue as far as alone time because her bedtime is 8 and she falls asleep in 2-5 min we give it about 10 min to make sure she is out when moving her but she is getting bigger (currently 6) and hard to carry for me because she is half my size and weight and she is a small girl as am i. My fiance has problems picking her up due to mulitple injuries with his collar bones and shoulders over the years. We only let her sleep with us when she wakes up from a bad dream because we have a small bed and we dont all fit mostly because his daughter. She is tiny but will take up half the bed lol. Is there any way to get her to be ok with her falling asleep alone at night. We have tried a night light but she still doesnt sleep. At her moms she has sisters in her room so she is never alone but she goes to sleep late like around 9:30 due to the other girls keeping her up.