It'll take between a week to two weeks to get her used to sleeping in her crib and it will probably be harder for you than her, but if you can stick through it, it'll be worth it. Even after the two weeks, there will be periods over the next few months that you may have to do this again, but I know from experience that it works. Now is the best time to do this because the older she gets, the harder this will be.
I'm not sure if you or your aunt puts her to sleep, but whoever is there around bedtime, which can be anywhere from 7:30 to 9:30 depending on what works best for your daughter, will have to be the one to start this. You may start and your aunt may have to pick up up when you leave for work.
Pick the same time every night. For about a half an hour, pick some kind of routine that will be consistent. Maybe read her the same three books, ending in Goodnight Moon (that's what helped us through this.) After you read that book to her, turn the lights out and go around whispering goodnight to everything. This will get her used to knowing when it's time to go to sleep for down the road, but this is where the fun starts.
Put her in her crib and say goodnight. You have one of two options, depending on how you feel. Either sit in the corner of the dark room looking away from you, or sit directly outside of her door. Because she is used to seeing you and being with you, I'd stay where your visible. Every five minutes or so, go over and soothe her, trying to do it without picking her up, but if you do pick her up, stay in the room. Your goal is to continue reducing the amount of time you're holding her. When you do pick her up, don't talk or sing and make it brief. After you put her down, DON'T LOOK AT HER! You want her to know that she's safe, but the interaction that comes from just a look will prolong the whole affair. Eventually, she will tire herself out, but not before she tires you out!
Just to warn you, this may go on for hours and hours each night. DON'T GIVE UP! You'll get to the point that you think you're torturing your daughter and you just can't do it, but there's actually progress taking place, it's just not obvious. This may be the hardest thing you've had to do yet, but the rewards are most definitely worth it. Your daughter will be able to eventually soothe herself to sleep and you and your aunt will be able to enjoy restful night! If you give up, you'll have to start from square one later. You WILL start seeing an improvement. After the two weeks (hopefully before), she will be able to go to sleep easier. Each child is different, so the time depends on your daughter.
Good luck!