NDAs with prospective investors should include a non-circumvention provision.
I have sadly seen it happen twice that a (larger, institutional) investor bypasses the sponsor and steals their deal. A non-circumvention should protect against this.
Whether you should actually file a lawsuit against a capital provider for breaching a non-circumvention is, of course, a bigger question. Sponsors are poorly equipped to engage in a legal battle. Even if you have the legal arguments on your side, there is reputational risk and it will take a lot of time, money, and pain to reach a resolution.
