Two follow-up questions:
Sorry, to me your goals are so convoluted that it's really difficult for me to understand what you want - or what you are afraid of. I guess I misunderstood your fear. On re-reading this, it appears that you are afraid that your (common) defendant might seek to discover documents sent between you and the class action plaintiff's attorney that the (common) defendant might not otherwise have access to via discovery.
I think anything that you send to the attorney (who does not represent you), and that they send to you, is subject to discovery by the defendant. But I don't see why it wouldn't have already been anyway.
You should ask this question to the class action attorney who "has routinely used joint-prosecution agreements in the past to coordinate efforts and to share information". But basically, like I said, if you don't trust that the "joint-prosecution agreement" will be to your benefit, and you don't trust the attorney who drafted it to be 100% on your side (which IMHO you shouldn't), then either don't sign it or get an attorney to help you with it. The bottom line is that the whole idea of trying to convince a class action attorney to file suit against your defendant so that they will share their discovery with you seems really convoluted to me.
Mark (and Quincy), thank you very much for your responses, which are really helpful.
As I believe an earlier post in this thread mentioned, I cannot prevent one or several class-action firms from piling on to my pro-se lawsuit once it becomes public, so I might as well try to influence the choice of the firm that might lead such an effort if the eventuality arises. The class-action cause of action is actually less complex than one of my other, completely unrelated claims in terms of established precedents, while several of my other claims involve equally thorny issues of international procedural and substantive law.
Most good attorneys specialize and are unlikely to be well versed in all or even several of my unrelated claims. While undoubtedly they, and some of the posters here, could run rings around me in terms of legal procedure, I can hold my own in crafting legal arguments and have a better understanding of the facts--both explicit and tacit--to winning my case. Even though the nature of most, or all, of my claims should enable me to recoup the legal fees (or share much of what some here would call the miniscule expected value of my (1) chance of winning multiplied by (2) any award or settlement), I am not willing to front (or pay) those costs.
(Hopefully) final question: would I have free access to any discovery conducted by a law firm that is not representing me but is engaged in a parallel action for class plaintiffs, to which you, Mark, said I could not belong due to my own related suit? Or for most of the stuff that work-product privilege does not protect such as direct quotes in transcripts or notes, could they require me to pay for it or to share in the cost of e.g. witness fees at trial etc?