in reply to @ 2015-352 03:36 UTCThat's not how copyright works. Your changes are always your own. However, in order to be allowed the use the parts from the original at all you must abide by the terms of the license. In this case, that means your schematics must be BY-SA as well. If you want to work out specific details of how that applies to specific things you want to do I suggest you engage a lawyer who specialises in copyright.