Hi @Diu, there is no way to rewrite breakpoints. I think the best solution at the moment is to define your own css media queries, using the same principles found on this topic:
You would need to create the media queries for each screen min/max dimensions you want to use, then target the classes used in the designer to be a certain dimension within each media query. It certainly is not as easy as using the built in breakpoints, but it is possible to do this using custom css in your header. Please note, those custom media queries will not show until publish.
I hope this helps, cheers, Dave