Ask HN: How common is it for an investor to ask for this kind of option?

We are currently in the process of raising our first round. One of the investors we are talking to wants the option to get 4% at a valuation event (≈100× the current round) or at any exit event, at the cost of the current round. They want to be able to allocate this equity to mentors they bring in and/or to partners in their own company, as they are a strategic/hands-on investor for us. This is on top of their commitment in this round. We would set up KPIs to unlock the equity. Are similar terms common? How will they affect us in future rounds?