Hey, thank you. That's a very reasonable solution. I'll try and work it out with her and if it doesn't work, then I'll speak to my main supervisor and hope for the best. Thanks again!

Hi! I started my master's earlier this year and I have a great advisor. My co-advisor, on the other hand, even though she's great and helps me a great deal, sometimes I think she helps me too much. She constantly performs the experiments without me knowing and then tells my advisor about the results and sometimes when I'm doing them, she tries to take control of the process, by telling me how to do it - her way, not necessarily the best or the right way - or she just sits on my place and starts doing things herself. It feels like my project is hers and I'm just an intern or someone who does the experiments instead of a master's student. Every Monday we have a lab meeting and yesterday was my turn to present my results. When people asked me questions, she talked over me and once she even talked over my advisor. People noticed and now I know it's not just a product of my imagination. And I really don't know how to deal with it because when I actually need her help, she's great. I just feel like she doesn't know her limits and I don't know how to set them without hurting her feelings.
Any ideas? Has anyone ever been through something similar?