Making SVG objects different depending on the color doesn’t seem a good option for an SVG exporter. So you could make a script to automate the changes inside your SVG in order to fill blue curves.
The other solution is to use another type of object for “blue” curves.
In Rhino : Hatch or Surface ? Don’t know if it will work
In my exporter I could extract “blue” curve from a surface. So all objects being surfaces could be filled by default and not curves.