I am a fifth-year CS PhD student in an US institution, co-advised by two professors, and I already passed my thesis proposal in the fourth year. In the thesis proposal, I promised to deliver one last project, in addition to three past projects that I have completed before the proposal.
I also presented a roadmap for graduation during team meetings, and discussed that with both of my advisors. They seem to be ok with it, at least neither of them opposed to what I presented. In the roadmap, I essentially said that I will conclude the project by June this year, after which I just start writing the thesis, and I expect myself to graduate by November.
Earlier this year, I already got preliminary results for the last project, and I am ready to write the last paper for submission before starting the thesis process. Then one of my advisors told me that I need to conduct extra experiments (which is fine), plus doing X and Y which he thought would make the results better (which is not fine, because X and Y are largely just his own research ideas, which do not fit into the last project I proposed). The other advisor's attitude is not clear when I tried to talk to him regarding the project arrangement, and his answer is always pretty vague, being something like "yeah you can graduate this year, as long as you wrap up the project".
I am now pretty concerned of my graduation status, because I was receiving conflicting messages here: (1) Both advisors seem to be OK with the roadmap I proposed; (2) But they said I need to wrap up the last project with research idea X and Y, which I totally do not know how to perform, because they are not aligned with my past research experiences. Besides, designing and preparing experiments on X and Y would take time, which I doubt can be done in a few months of time; (3) Meanwhile they still say that I can graduate by the end of this year. I do not know what do those conflicting feedbacks mean, and I need help. Should I just tell them I am unable to perform X and Y, and please just let me graduate with the current projects? Or should I just try my best until they decided that I have done enough or simply until they give me up?
I am also a little bit upset about the fact that I did deliver what I have promised, and all three of us had agreed that I could graduate after that, but still one of my advisors insisted that I should do X and Y and pressed me to add them into the last project. Worst of all, X and Y are out of my research focus, and I have neither the slightest idea nor the experience on how they could be done.
By the way, the reason that I strongly wish to graduate by the end of the year is that I already got two job offers, and I really want to accept one of them. It would be a lost opportunity if I could not complete the degree by the end of the year.