I have a scenario where someone I know is up for a promotion within the next 12 mos. This person works at a larger software company, and would like to arrange a moonlighting allotment in order for them to pursue a (non-software related) small project that had shown promise in the past. I know that promotions usually come with changes in salary and responsibilities, and sometimes benefits, however, are changes in agreements, such as moonlighting, typically something that is negotiable? How hard can one reasonably push the envelope with this issue (given one isn't looking to change jobs)?
Additionally, Would it be better to negotiate with HR or the Manager first given that both are met with in the process of being promoted?