Hi Mike,
Let’s assume you want to use the 7k mic input and DSP for the vocal because it’s better than the mic input on the laptop, particularly down the usb connection. To obtain the backing track for timing first record it to audio on the laptop on its own. Now you can get the vocal on its own down the 7k mic input and usb connection at a far better quality than most laptop mic inputs without the backing.

There are various possibilities how to now sync your timing to the backing for the vocal. You could just listen to the backing on the laptop headphone out, but this is likely to be a little weak. Another method would be to feed the analogue line out of the laptop to the aux in of the 7k with stereo audio cables. Now go to the Sound Menu and Monitor and set to OFF. The speakers and headphones (which will have a more powerful drive than the laptop headphone amp) of the 7k will play back the backing audio tracks but isolated from the mic input. Naturally the recording program options will now need panasonic audio usb on the input for the mic, but laptop wave out on the output. You can now record the vocal audio through the 7k mic input and DSP and the usb connection digitally to Cakewalk or whatever to a separate track without any sequencer backing. Then just erase the audio backing tracks and save the vocal wave, and convert and check out to SD.

The only remaining problem is eventual final sync of audio vocal track on SD to sequencer playback. If you make sure to have the start point of sequencer backing playback and laptop audio backing recording at the same time, and then start the vocal audio recording at the same time as the audio backing playback you may not even need to do anything. If the vocal sync is slightly out with the sequencer it can be tweaked backwards and forwards in the 7k with the SD Audio Synchro function in the Sequencer menu.
Happy Holidays