My four month old Granddaughter only sleeps in her swing is she going to be hard to break from this?

I did this with my second child out of sheer desperation. The rocking motion of the swing was the only thing that would get her to bed at night. I was exhausted, my husband was exhausted...and then we figured out that if we put her in the swing she would fall asleep. We would then transfer her out of the swing and into her crib or the co-sleeper. My belief is that parents have to work with whatever methods give them peace of mind and provide a happy, healthy home environment for the entire family. Honestly, it wasn't too hard to break my daughter of the habit. As she got older she became more settled into a daily and nightly routine and we no longer relied on the swing. I must say it was a godsend. The best baby gift we ever received!