I have worked at a very large, bureaucratic MNC for the past two years, and about five months ago, I got the raise and promotion I had been campaigning for in the ~6 months leading up to it. About a month after my promotion, my mentor up to that point gave his notice, and left on good terms. He and I worked very closely on an extremely legacy product that is not well known outside or even inside the company.
Since my mentor left, I have inherited a lot of the “overhead” type work he was doing, in addition to the more technical work I was. Right now, we have two others I have been actively training in this legacy product, but due to some personal goals of their own and other requirements, I wouldn’t say either of them has the knowledge base I currently posses.
Question: since my mentor left, I feel I have taken on a lot of work. Given that he was with the company for nearly a decade, I know he was making much more than I am now at the time of his departure. I feel that I should be reasonably compensated for the additional work and level of work I have taken on, but in such a large company, I am not sure that even if my manager wanted to, he could get another medium-sized promotion or raise for me so quickly after the last one. I know that the bi-annual period for raises is coming up. How can I effectively make my case for a promotion without appearing ungrateful or having to “play hard ball?”