It sounds like she may be. If you wanted to, you could get an ABR (Auditory Brainstem Response) done on her, like a human baby, but i wouldn't worry about it. She is what she is, and she has a family to love her. Her sibs will probably clue her in to sounds around her, and you can communicate with her via vibrations, light flicks, etc. You may find there are some intensities or frequencies that she can hear, which you can use. If you feel like going high-tech, you could try a vibrator receiver collar when she's bigger.

Syndactyly and hearing loss won't hurt her at all.