Developing on Nathan's findings:
It might be possible but would require replacing those bearings, if one can be found with smaller balls and therefore a larger inner diameter hole.
Your existing 15x26x7 is a common size bearing, where 15mm is the internal diameter, 26mm is the outside diameter, and the cartridge is 7mm thick.
If you were to use 16 or 17x26x7 then you'd have 1 or 2mm to work with, resulting in a locating flange of 0.5 or 1mm in thickness. That's not a lot.
Upshot - it might be possible but you're in the realms of custom machining. Last time I got something small like that made it cost me $hundreds and that was a decade ago. If you know someone with machining skills and equipment, then it might be possible but there are always inherent risks when prototyping bike gear.
You may be better off selling these wheels and buying a new pair that suits your needs now.