7.2 Dayton Audio Build from Scratch. IMPEDANCE QUESTION!

So my buddy and I are planning out a 7.2 home theater sound system from scratch. We are planning on using Dayton Audio Reference drivers. None specifically picked yet but most likely 7" woofers in the towers for midrange and a 1" tweeter for the highs. We are planning to do T-Line boxes for the Subs. But that's another story. Our main roadblock so far is that while researching and designing our crossovers we cant figure one thing out. Do crossovers affect overall impedance? If we have 2 4ohm 7" drivers and a 1" 4ohm tweeter, is there a possible combination of series/parallel wirings that will make it 8ohms overall for the tower or do we have to add an extra 4ohm driver?

Thanks in advance.