Glad to hear that (slooowwwwlllyyyy) things are getting better with this little girl. I agree that lots of hugs and snuggles and reassurance during waking times are required, with slow transition to her being a lot more independent. But I think at naptime, I am with kangaroomama in that she needs a naptime routine and a bit of a cry-out when required. That is an unfortunate aspect of multi-child care. We as providers simply do not have the luxury of attachment sleep training. I would cuddle her while putting her down on a decreasing schedule (ie; 10 minutes at first, or as needed, then 8 the next day, then 5, and so on).
Good luck, and hang in there!!