Sorry this will be a long one but I just dont know how to handle this situation.

I just started my job about a year ago and grew extremly fast in my role because I was a very quick learner and I pushed to learn more. Even though I got more and higher responsibilities than others who worked there a lot longer I am well liked. The average age of my co workers is mid 30 and I am only 21 which hasnt bothered anyone. My supervisor really bealieves in me and she knows, that when she needs something done perfectly she can come to me. I also currently work towards my management degree which is an other reason my suppervisor pushes me towards bigger roles. 

Just a few weeks back I started a new project and I had to keep it more or less a secret from our counterparts from the other shift beccause one person, lats call her Rachel, likes to "steal" projects by saying she already started the same project and is almost done but wont show any work and wont be done for months. Last Thursday I finally had a talk with her and she would say over and over "I understand BUT management cant force us to do this" and "we cant take on more work and not get extra people they CANT force us" (4 more minutes of work a day while reducing the wait time by half an hour a day). I tried to stay as calm as possible and explain her that management made this decission and we need to make it work and it actually benefits us a lot. The next day I saw in my emails that she just set up a meeting about my project to discuss my ideas. I replead with a professions email asking for a cancelation because as of right now I only have ideas but invenotory, units planning and engineering didnt let me know yet if these ideas are actually possible. My worry is that we have a meeting with all these people and talk about ideas which turn out to be impossible or we just end up saying "we need to research this more". In my email I stated that I would set up a new meeting next week because I would ahve definite answers by then but she still declined to cancle this meeting. My supervisor doesnt understand my frustration that Rachel just went above my head.

Rachel just started to train her personal minion (I'll call her Heather) and well both of them tend to look down on everyone as if they are barely good enough to sweap the floor, in meetings they keep on roilling their eyes, and if I (or most other people) will tell them something they wont believe it because they assume we are stupid. 

I am extremly patient but slowly I just get so frustrated that it becomes extremly hard to be professional around them. Some times I wonder if I should call them out on their behavior, for exmaple if they roll their eyese just ask if I should explain it a big better because they look sceptical. Any suggestions on what to do? Like I said my supervisor doesnt really care about it or doesnt do anything about it.