hey brother, well, the chest/ab/diamond/collar/shoulders all attach to a flak vest, not the flightsuit...the knees are sometimes held onto the flighsuit with velcro or snaps, and of course the strap that goes around the back of the knee...the backplate attaches to the collar plate, and then usually just hangs down from the shoulders, especially if you are using a jetpack, the weight of the jp will hold the backplate down to your body...some put velcro on the inside of the backplate and on the flightsuit as well, but not necessary...
the cod connects to the kidney/butt plate, ideally...some armor you cant do that, unless you make some kind of extension to get them to meet up at the hips...these once again can have snaps strategically placed or velcro as well...
do a search on armor attachment, there are alot of threads will work in progress pics to show you what alot of talented members have done...give me a shout if you need more info...