Tom,
You have too many of the same band antenna's concentrated in one place.
No matter how hard you try, they aren't going to play nice with each other.
I read 14 posts and no one gave an even close right answer to your question.
The answer is that you need to construct a tower, no less than 100', near your house in order to even try to do what you wish to do.
Even then, you will need feet of separation vertically in order to get the antenna's to play nice with each other.
Your SWR is going to be all messed up, because you have too many of the same antenna's in the same proximity.

The only good 6 / 2 / 70 cm antenna that I could recommend would be the Diamond v2000. This is the only antenna that I am aware of that has a decent amount of gain - if you want to call it that, along with being semi resonant on all three bands.

What you are doing is back-feeding everything that you transmit back into the receive of the front ends of all of the radios in your shack when any one radio transmits. Unless it is in your budget to replace all those radios on a semi annual schedule, you will eventually experience that each of those transceivers will eventually become deaf.

I have seen filters promoted in QST that allows two operators on two different bands to share a beam antenna with two transceivers, as long as each transceiver stays on it's band it is ok.

But there is a hell of a difference between 20 meters - 14 MHz - CW and 40 meters Phone.

Even though 70 cm is not a harmonic of 2m, and even though there is a heck of a disparity between 440 MHz and 146 MHZ there is always going to be problems when dealing with FM, and Digital modes.

I have to take your wife's side on this one!

Tell your club to go out and buy an acre of ground and put up a transmitter and a tower and put their packet and their D-Star crap on their tower, and then you can tune to their tower frequency if you so choose. You are killing not only all of your transceivers by what you are trying to do, but you are diminishing the range at which you yourself can operate...

If you can hear other repeaters / more than 20 miles away though all of that RF noise you have created, you will be lucky..

It doesn't matter if the radios are all turned on or off, as long as they are connected to the coax / antenna, they are still going to experience front end overload.