Acquiring the "B" in a B2B2C biz model

In the case of food delivery startups, the pattern seems to be:

1.) Acquire initial "C" users by offering B's product via a better experience at no extra cost, and without telling B. The orders placed on your site just get manually called in.
2.) Approach B only after enough Cs have changed their behavior and are ordering through you. Now you have a much better negotiating position, and you can ask B to give you a commission on each sale, or else being locked out of your marketplace.

This basically requires operating at a loss for a while, burning through capital while you try to establish a position between the Bs and Cs, while also competing against other food delivery services in a land grab.

It remains to be seen whether this is a sustainable model for food delivery, nevermind whether it is generalizable to other areas. One reason why it seems well-suited for food delivery is that consumers can make a new buying decision every single time they order a meal, which is an opportunity for the middleman to influence that decision and extract their cut.

I don't think the same is true of youth sports leagues. I suspect there's virtually no risk that a teenager will switch to a different league mid-season based on the quality of the software experience.

I also don't think leagues see themselves as being in heavy competition with each other for enrollment. Maybe things have changed since my youth sports days. Do they have marketing budgets? The amount they're currently spending on marketing would be a good indication of how much they'd be willing to give up in order to win in a competitive marketplace.

For these reasons, I don't think food delivery startups are a great model for your market. Again, I'm not currently in that world, and perhaps some of my starting assumptions are wrong.

A closer match might be Slack, especially in its early days. They appealed largely to developers, who would spin up their own Slack workspace to use at work. As it proved its worth, and as employers wanted to retain control over work-related communications, companies started paying for paid plans, and Slack usage expanded to other parts of the enterprise.

There's a similarity with food delivery, in that they got the "C" first, but there's also a big distinction in that they are not trying to insert themselves into pre-existing transactions between "B" and "C", and they don't try to exert any leverage to potentially hurt "B" by sending "C" elsewhere. In this way, I think they are both a "nicer" business, and more likely to match your market. So maybe some research into Slack growth stories would give you some ideas.

Supposing you did follow their lead, and offer a free version to your Cs that then gets up-sold to the Bs after the Cs have found tremendous value. There still remains the problem that youth sports leagues probably don't care very much about "owning" the communication channel used by athletes, coaches and parents. There has to be some other kind of value generated by a paid plan that would convince the leagues to purchase. Once you've got all those Cs, what can you offer the Bs to save them money, make them money, reduce risk, etc.?

Seems tough, because youth sports teams are usually pretty small. You could consider selling at the league level to get buy-in from lots of coaches simultaneously.

If leagues are as skeptical as coaches, maybe try going bottom up and allowing players to be app admins and then bring in their coaches later. Or try sports with larger teams (e.g. football) who might have more coaching assistants, who I'd guess are young, bored, and are therefore are easier to convince of something like this. Coaches might go for it if they can offload management to an assistant.

As for channels, I'd probably stick with one-one conversations until I learned more about what works. It's hard to get great feedback with 1-to-many channels or viral channels (although you might need viral if you go bottom up).