Copying multiple waveforms to clipboard

Hi everyone,
What’s the trick to copying multiple waveforms from a single station (my own) onto a single clipboard? For instance, I’d like to stack the four Pacific NW quakes onto the same clipboard. Each quake is separated by about 1 hour. When I copy the first quake to the clipboard it shows up just fine, as always. (image 1) However when I highlight new portion of the helicorder and copy it, the original waveform changes to the current selection (image 2). This problem has vexed me for a year, but I always forget to ask if there’s a solution. Thanks for your help! (running Swarm 3.0)