diff --git a/package.json b/package.json
index 7683ec4..f7068f3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@jogogo/mhysa",
-    "version": "2.0.0-alpha.3",
+    "version": "2.0.0-alpha.4",
     "description": "Streams and event emitter utils for Node.js",
     "keywords": [
         "promise",
diff --git a/src/functions/demux.ts b/src/functions/demux.ts
index 6d4d093..fdc9063 100644
--- a/src/functions/demux.ts
+++ b/src/functions/demux.ts
@@ -9,30 +9,42 @@ export interface DemuxOptions extends DuplexOptions {
 }
 
 export function demux(
-    construct: (destKey?: string, chunk?: any) => DemuxStreams,
+    pipelineConstructor: (
+        destKey?: string,
+        chunk?: any,
+    ) => DemuxStreams | DemuxStreams[],
     demuxBy: string | ((chunk: any) => string),
     options?: DemuxOptions,
 ): Duplex {
-    return new Demux(construct, demuxBy, options);
+    return new Demux(pipelineConstructor, demuxBy, options);
 }
 
 class Demux extends Duplex {
     private streamsByKey: {
-        [key: string]: DemuxStreams;
+        [key: string]: DemuxStreams[];
     };
     private demuxer: (chunk: any) => string;
-    private construct: (destKey?: string, chunk?: any) => DemuxStreams;
+    private pipelineConstructor: (
+        destKey?: string,
+        chunk?: any,
+    ) => DemuxStreams[];
     private remultiplex: boolean;
     private transform: Transform;
     constructor(
-        construct: (destKey?: string) => DemuxStreams,
+        pipelineConstructor: (
+            destKey?: string,
+            chunk?: any,
+        ) => DemuxStreams | DemuxStreams[],
         demuxBy: string | ((chunk: any) => string),
         options: DemuxOptions = {},
     ) {
         super(options);
         this.demuxer =
             typeof demuxBy === "string" ? chunk => chunk[demuxBy] : demuxBy;
-        this.construct = construct;
+        this.pipelineConstructor = (destKey: string, chunk?: any) => {
+            const pipeline = pipelineConstructor(destKey, chunk);
+            return Array.isArray(pipeline) ? pipeline : [pipeline];
+        };
         this.remultiplex =
             options.remultiplex === undefined ? true : options.remultiplex;
         this.streamsByKey = {};
@@ -53,43 +65,66 @@ class Demux extends Duplex {
     public async _write(chunk: any, encoding: any, cb: any) {
         const destKey = this.demuxer(chunk);
         if (this.streamsByKey[destKey] === undefined) {
-            const newPipeline = await this.construct(destKey, chunk);
-            this.streamsByKey[destKey] = newPipeline;
-            if (this.remultiplex && isReadable(newPipeline)) {
-                (newPipeline as NodeJS.ReadWriteStream).pipe(this.transform);
-            } else if (this.remultiplex) {
-                console.error(
-                    `Pipeline construct for ${destKey} does not implement readable interface`,
+            const newPipelines = this.pipelineConstructor(destKey, chunk);
+            this.streamsByKey[destKey] = newPipelines;
+
+            newPipelines.forEach(newPipeline => {
+                if (this.remultiplex && isReadable(newPipeline)) {
+                    (newPipeline as NodeJS.ReadWriteStream).pipe(
+                        this.transform,
+                    );
+                } else if (this.remultiplex) {
+                    console.error(
+                        `Pipeline construct for ${destKey} does not implement readable interface`,
+                    );
+                }
+            });
+        }
+        const pipelines = this.streamsByKey[destKey];
+        const pendingDrains: Array<Promise<any>> = [];
+
+        pipelines.forEach(pipeline => {
+            if (!pipeline.write(chunk, encoding)) {
+                pendingDrains.push(
+                    new Promise(resolve => {
+                        pipeline.once("drain", () => {
+                            resolve();
+                        });
+                    }),
                 );
             }
-        }
-
-        if (!this.streamsByKey[destKey].write(chunk, encoding)) {
-            this.streamsByKey[destKey].once("drain", () => {
-                cb();
-            });
-        } else {
-            cb();
-        }
+        });
+        await Promise.all(pendingDrains);
+        cb();
     }
 
     public _flush() {
-        const pipelines = Object.values(this.streamsByKey);
-        let totalEnded = 0;
+        const pipelines: DemuxStreams[] = [].concat.apply(
+            [],
+            Object.values(this.streamsByKey),
+        );
+        const flushPromises: Array<Promise<void>> = [];
         pipelines.forEach(pipeline => {
-            pipeline.once("end", () => {
-                totalEnded++;
-                if (pipelines.length === totalEnded) {
-                    this.push(null);
-                    this.emit("end");
-                }
-            });
+            flushPromises.push(
+                new Promise(resolve => {
+                    pipeline.once("end", () => {
+                        resolve();
+                    });
+                }),
+            );
         });
         pipelines.forEach(pipeline => pipeline.end());
+        Promise.all(flushPromises).then(() => {
+            this.push(null);
+            this.emit("end");
+        });
     }
 
     public _destroy(error: any, cb: (error?: any) => void) {
-        const pipelines = Object.values(this.streamsByKey);
+        const pipelines: DemuxStreams[] = [].concat.apply(
+            [],
+            Object.values(this.streamsByKey),
+        );
         pipelines.forEach(p => (p as any).destroy());
         cb(error);
     }