As a quick fix, I think you could probably take them up at the shoulders. Would require recutting the neckline and the armscye possibly and rebinding that, but that is usually a "quick fix" I do on my own stuff (being short waisted).
I don't necessarily think they are too big in width, just that the waists look low.
Possibly you only need to take the shoulder up on the back part. Possibly this could be some form of hollow back? Or just that both girls are that shape where they have tummies and a rounded front shape.
I'd start by pinning up the back as the sleeves only, see how that goes, then pull up a little from the front too. Does the waist elastic dip forwards?
I'm just speaking from my own personal problems in this area, not an expert!