Gadgets can interact with Fluids! Make sure Raytracing Fluids is enabled to select a fluid with shift-rightclick.
To place fluids in the world, you'll need a bucket with the appropriate fluid in it.
Alternatively, mods that add tanks (like Mekanism) can be used, and the fluids will be removed/inserted into tanks.
Fluid Handling
Switch the images above to see the different options
The copy paste gadget, can of course, handle fluids as well!
When undoing or exchanging fluids, the gadget will try to find a place to put the fluid (Like an empty bucket or tank) but will void the fluid if one is not found.
Fluid Handling
Copy Paste Fluids