Good point. Every University and even college/school and department can differ on their policies and requirements. My answers were based on my experiences and I think are fairly representative of a situation where a doctoral student is receiving funding through a federal grant mechanism where there are restrictions based on salary and time. During my masters I received a fellowship through the University (not a federal grant) where I was required to teach and do some research. If the OP's wife is getting funding internally, then who knows what the requirements and expectations may be. But, it sounds like the $ was coming from a extramural grant.