Dear colleague,
I supposed to have a new Ph.D. student for an NSF-funded project, but issues come up so that the student cannot start this spring semester.
Instead of the student, I plan to ask my research staff to do the project. In this case, could the Ph.D. student budget be used to support the research staff?
Check with your sponsored programs office and grants accounting. I would assume that you might need to ask the program director who can (unofficially) allow to use the funds in some other way or ask you to officially re-budget with NSF.
Unless the student was being paid out of participant support (line F on the budget) or unless this change affects the scope of the project, this shouldn't require a formal notification/request/rebudget with NSF (though it can often be prudent to notify your program officer of events like this just in case). However, your institution may have stricter rules than that, so I'd start with your sponsored programs office.