Ask HN: Keeping a co-founder aligned with our interests

We have a potential co-founder who can possibly bring in investors based on a solid track record of doing so with other businesses. Instead of being rewarded with a finder's fee, she wants to be rewarded with a share of our company. She plans on putting effort into helping us grow. Our first thought was allowing her to exchange the usual finder's fee for discounted shares. With the shares being priced according to the deal with the first investor. However that aligns her interests with the investor. They both want the maximum number of shares for the lowest price possible. How can we create an agreement that rewards her for finding investors while keeping her aligned with our interests to get a high initial valuation from potential investors?