I believe they sell the parts, but you probably have to do that to your shoes yourself. They actually don't recommend people to do that because a sneaker isn't as supportive nor is it made to be a roller skate, so do that at your own risk.
Check out Sk8 fanatics custom skates they are on FB I believe. This shop doesn't do skates with tennis shoes. They may have some recommendations though they are friendly helpful staff.
Skyler
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