Resulting Image (white balance corrected); notice the lack of sparkler sparks from cheapo $0.99 cent sparkler pack.
Step 2: Duplicate this new image layer, and apply a Gaussian Blur filter somewhere high - radius around 65 or so, set to about 90% opacity.
Step 3: Duplicate that blurred layer and change the Hue/Saturation sliders - hue moves left and saturation moves right, set to about 80% opacity.
Step 4: Add a matte layer (curves adjustments) at 40% or so.
Step 5: Optional: I added a colorful texture background layer set to Color Dodge at 20%
Step 6: Optional: I added a radial gradient (orange to red) set to soft light at about 55%
Step 7: Go back to your bottom layer (the new head-swapped layer) and use the Quick Selection Tool to select only the subjects. Then go to Layer > New > Layer Via Copy. Drag this layer to the very top layer.
Step 8: Now your subjects will stand out very strongly against your pretty blurred background and they will have a halo around them. So go back to your first blurred layer and using a very soft (15%) black brush, paint off some of the blur around your subjects - so essentially we are adding flyaway hairs back in, adding back the bubbles and adding foreground around the feet for a more realistic and less choppy look. Keep painting off the blur to suit. Then lightly paint of the blur surrounding the subjects from the next blurred layer as well.
Step 9: Find a sparkler image on the web - there are tons - one with a black background. Drag it on top of your layers and re-size/rotate to make it match where it would be in your photo. Then set layer mode to Screen at about 45% - this gets rid of the black background. Duplicate this sparkler layer and set the mode to Lighter Color at about 75%. Paint off unwanted areas and Touch-up as needed.
Step 10: Review and zoom in and lightly Paint on/off various layers to tweak and touch-up. Wallah!