Engagement journalists use the word “callouts” to describe requests for information from readers or viewers, including submission forms, dedicated email links, etc. Thinking about and designing effective callouts is worth a guide of its own, but this will get you started.
It's important to coordinate a launch date with your partners so you can all publish your tip submission forms on the same day, and each newsroom should prepare an article or segment about the project to recruit participants from their audience and explain to them what you're hoping to achieve. Coordinate on the technical details but leave your partners room to speak to their audiences as they know best. That connection is what made them attractive in the first place, isn’t it?
Once you settle on a format for launch stories, be sure to coordinate press outreach and social media/newsletter distribution. Creating buzz about the project will help get more eyeballs on your tip form. A shared Google Doc among social media teams can work wonders here.
As part of that outreach effort, identify organizations and people who care about this particular issue and who might be willing to spread the word about the project and have access to the communities you need to reach.