It is fine for her to sleep in a semi-upright position, but she will soon outgrow the seat. She'll be big enough to tip it over, roll out of it, or wiggle and get tangled up in the straps. So it's probably wise to solve the problem in another way. She most likely responded well to the snuggly, contained feeling of the seat while the more open crib allows her too much wiggle. Swaddle her in a light receiving blanket with her hands up by her face. Put her at one end of the crib next to well-attached bumper pads. Be sure she is on her back, on firm bedding, with no pillows or fluffy bedding around. Another part of this "problem" may be that she is now at the stage of brain development when her sleep is more easily interrupted; earlier her sleep was more determined by her own internal regulation. So she may be going through a change that has nothing to do with where she sleeps. With your support, she'll get into a new, more mature sleep pattern.