code: function(url) {
              var needle = url.replace(/^https?:/, '');
              var assets = µb.availableFilterLists, asset;
              for ( var assetKey in assets ) {
                  asset = assets[assetKey];
                  if ( asset.content !== 'filters' ) { continue; }
                  if ( typeof asset.contentURL === 'string' ) {
                      if ( asset.contentURL.endsWith(needle) ) { return assetKey; }
                      continue;
                  }
                  if ( Array.isArray(asset.contentURL) === false ) { continue; }
                  for ( i = 0, n = asset.contentURL.length; i < n; i++ ) {
                      if ( asset.contentURL[i].endsWith(needle) ) {
                          return assetKey;
                      }
                  }
              }
              return url;
          }
docs: https://github.com/gorhill/uBlock/issues/1181 Try mapping the URL of an imported filter list to the assetKey of an existing stock list.