Replacing factory amped 3 way components with 2 ways, keep factory mid?

the vehicle is a 2010 Lexus RX450h standard audio w/ factory nav. the front doors have factory amplified and crossed over 3 ways. the tweet(capped) and mid are fed by one signal from the amp and the door woofer is fed separately by the amp. the rear doors are two way components fed by one line from the amp. the sub is dual 2 ohm i believe.

i have two sets of rockford fosgate T165-S 2 way components with bi-amp capable passive crossovers im planning to install in the front and rear. also installing a alpine pdx-4.100 amp and a pdx-1.600.
i have an audio control LC8i to use as an active line level converter and it's capable of channel summing so i can construct a full signal to feed the front doors (if you think that would be the best route)

heres what i want to know. what do you think would be the best way to set this up?

1. Nix the factory mid? and use the lc8i to build a full signal which will be amplified then split at the crossover and feed the new 2-way components?

2.keep the factory mid? fed by the factory amp then use the lc8i to sum the high and low signals from the factory amp to feed the aftermarket 4ch and send a full signal to the passive crossover in the door which will drive the aftermarket tweeter and woofer while the mid remains powered by the factory amp?

3. something else?