I was hoping me deleting a couple of the worst posts on the first page would be warning enough, but I see it wasn't. No matter how much of a noob another member may be, or how much you disagree with his/her plans, that does not give you the right to be insulting. This forum is here for people to discuss car audio, to teach, learn, and socialize about it. Its easy to post a helpful, friendly, respectful reply while also saying you disagree with his/her plans, here let me show you.
I disagree with building a rear sound stage that will overpower your front stage, it inhibits your stereo's ability to accurately reproduce the 3-dimensional space the band recorded it in. Remember, your music was recorded in 2 channels, 2 front channels, not 2 front channels and 2 rear channels. So obviously reproducing it with 2 rear channels that can easily overpower the fronts, will make it loud, but not very accurate to the recording.
Okay, that being said, you dont want to 'splice' speaker wires together. If you wanting to wire multiple speakers to same the amplifier channel, you do it via parallel/series (or a combo of both) and you do it at the speakers, or at the amplifier terminals. Physically splicing wires together can work, but it has some potential problems that could occur, which is why most people use the method I am suggesting here.
Lastly, all those different speakers no doubt have different impedances (yes, even if they have the same advertised nominal impedance). That means each speaker will receive a different amount of power from the amp. Add to that the different design features of the speakers that alter their frequency response, and now you have this big mess of multiple speakers playing at different volume levels, with different frequency responses, and there's basically nothing you can do to adjust each one individually because they are all hooked together. It would be a nightmare for tuning, and would most likely sound very badly. What you are suggesting is possible, but I definitely urge you to go a different route. Just because you own all those different speaker sets does not mean it would be advantageous to use all of them.
Now that Ive shown how easy it is to disagree with someone in a respectful manner, I expect everyone here to follow my lead. I will also stop simply deleting replies that break the forum rules about insulting other people, the consequences just went up. You guys have been fairly warned here.