Hi Michelle, not sure what advice I can offer you, but I have had very similar problems with Jacob, when he began nursery. I guess I am quite lucky, in that the staff are quite good in many ways, but they did (and still do sometimes) have difficulty in carrying through the requests I make about sleep.
Jacob was always a 45 minute napper, and sleep is something we have had to work hard at.
I was wondering whether the nursery would let you introduce Megan very slowly, in a graded way. This is what we did - starting with me being there for a couple of visits, then leaving him for 1/2 hour - 1 hour - 2 hours - a whole morning and finally a whole day. We transitioned this over 2 weeks and he settled in ok, (he was 6 1/2 months)
Also, having just one allocated nursery Nurse to begin with really helped Jacob, so he could make an attachment more easiliy, before being introduced to anyone else. Perhaps you could suggest this?
The things that I have done to try and improve the situation, regarding his sleep have included, trying to build up a really good rapport with staff (!), actually being there for his first ever nap at the nursery and showing them how I do it, talking lots about BW methods to try to get them interested!, explaining and educating them about the methods I use, lending them my BW video, also giving them and Jacob time to get to know each other and to get used to the new environment.
Alot of this has worked, the problem which tends to crop up is when he goes through different stages which may affect his sleep, or for example (like now for me) trying to extend/ amalgamate naps. The staff at my nursery are quite young and do not have babies themselves, which I think makes a difference, as they don't quite understand the importance of sleep! They also have traditional views about sleep, eg, "if we keep him up for longer he will sleep better later!" It can be quite frustrating at times, but at least they do listen.
I hope this might help a bit, I'm sure things will get easier.
Good luck
Cheryl