You would be happily surprised at how good a 2245 / 2226 combo sounds.
If I were you, I would build, just for testing, a single 10cft cab for a 2245 and a two 5cft cabs for the 2226s. It will be cheap, and you can experiment with this combo. Use the 2245 up to 50/60Hz, then the 2226 up to 600/700Hz. That is a killer combo for bass at home. You get low bass and punchy kick. I wouldb't even bother with the 2118 as I think that they are great for vocal reinforcement but certainly not for bass.
Few more questions. Your two 2245s are 8 Ohms. Correct? And they are connected in parallel, giving 4 Ohm at the dividing network.
Lee
PS, to make things simpler for you, maybe you can keep all your drivers as is. Put aside the analog crossovers, and replace them with an active digital unit. Experiment with levels, phase and tonal correction. The you'll know what the system is capable of. At that point, you can decide if you keep and modify the analog filters, or keep the digital one. 3-way digital crossovers are cheap. 4-way systems are more expensive. So maybe you get a 3-way from Behringer to feed the 2245, 2118, and higher range as a combo including the analog crossover.
http://www.axemusic.com/live-sound/s...ontroller.html