Advice: Renewing workstudy term

[R1CED`]

hi revscene

looking for advice.

I'm currently going into my last year of university. This past summer I've been working at a workstudy job. Each summer position allows 20 hours/week. For those of you who don't know what that is, it's on-campus jobs that the university subsidze a majority of your wage..the rest is covered by a research grant in my case.

I was thinking about asking for them to extend my workstudy term into the academic year but my supervisor approached me first to ask if I wanted to stay on. She said the boss was happy with my work. They said they were hoping I could I work 20 hours/week but would understand if I can only do 10 hours/week because of full-time studies. I told them I can still do the 20/week. I've asked them how funding would work, they told me the university will only subsidize majority of the 10 hours, the rest will be covered by the office since the grant will have run out by then. I was happy with the decision.

My supervisor goes on vacation and while this time I was working at home (something they are cool about). Once she was back another supervisor in the office who oversaw some of the projects I did in the summer had informed me they were going to hire another workstudy student (someone who used to have my position, graduated but is coming back for another degree). This supervisor also told me my hours will now be 10/week. This caught me by surprise. I was actually going to ask for a small raise, but now that I can't even get my original hours I didn't ask haha.

Now my biggest question is how I should approach this professionally. I already budgeted my finances for the year considering I will be working 20 hours/week. Should I speak with my original supervisor that had asked me to work this much or just speak directly to the other supervisor taking care of the paperwork? My finances are tight but from my previous experience bringing up that I need more hours is a sensitive subject. I dont know how to approach this. I want to somehow ask in respectful manner if the office still has enough budget for me to work 20 hours now that they've considered adding another student. It's hard for me to ask straight up because the supervisor's office are right next to each other and their doors are always opened.

Thanks for reading.