Differnt Speakers In Parallel

[hy fy]

Greetings all!!!

In G.A. Briggs "Loudspeakers - The why and how of good reproduction", there is a small mention of the wiring of different size(type/impedance) speakers, in this case an 8" and 5", in parallel to obtain a flatter impedance curve, I can only find one reference to this deployment on the web:

http://www.webervst.com/sptalk.html (a response to G. Lopez)

Does anyone has any further input on this subject? Would the impedance seen at the amp alter the response of the drivers? For example, if the Ohms drop at Fs of each driver surely the drivers response will change? Is it possible to match two or more drivers to create a virtual crossover network within the driver network as a result of the varying impedance over Fs?

Could a bass speaker "take" the frequencies it needs and "give" the frequencies it cannot reproduce?

It could be of no significance or benefit but I'm sure you will agree a mutiway system from one amp without active or passive components should merit investigation.

Many questions....
and many thanks....