Since I now see that you are pre-formation and based upon Ms. Ginossi's correct comment, here's an additional thought.

If only one (1) of your octet signs the NDA with the investor . . .

(A) the NDA should provide notice to the investor that the company isn't yet formed, but that this NDA will be for the company's benefit (and perhaps the benefit of each of its shareholders) - in effect, your NDA will have third party beneficiaries (be as specific as practically possible), and

(B) the company (after its formation) can ratify the NDA by written consent, acknowledging the NDA as an action appropriately taken by individual X on the company's behalf. At that point, provided that your NDA gave the investor full and proper notice of the company purpose, your NDA will inure to the benefit of whoever you like.