How to do this kind of switching?

[shakti]

Probably a noob question, but here goes...

I am assembling a pedal board, and want to be able to switch two of the pedals from being either wired directly into the front of the amp, or in an FX loop. I don't need to do instantaneous switching so I don't need a footswitch, just need to be able to switch it around without physically rerouting/rewiring anything. A simple rocker or toggle switch on the face of the board would do it. Let me explain the signal flow a little more:

The basic outline is this; guitar goes into a Lehle D.Loop. Out of the Lehle D.loop into a Foxrox Paradox TZF flanger. Stereo out of the flanger into TC Flashback X4 (stereo in). Stereo out of the Flashback X4 into a Lehle Dual SGoS amp selector/switcher. With this setup I can use these two pedals in stereo (or mono) directly into the front of the amps du jour. They both sound killer in stereo this way, particularly with clean amps.

HOWEVER...sometimes I use amps with an FX loop. Into a dirty amp, both delay and flange sound so much better after the preamp, so it makes more sense to have them in the loop.

Here comes to question; what type of switch would I need in order to be able to switch these pedals from being in line in front of the amp, to being in a loop of their own? If I ignore the ground connections, I've drawn up a diagram for a 3PDT switch which should take care of it, but my stupid question is this; can I get by without switching the grounds? Aren't the grounds tied together anyway? Or would I end up with a nightmare of ground loops?
If I need to switch the grounds at the same time, would I need a 5PDT or 6PDT switch? Can I get by with a common ground connection for the stereo connections?