This is a cool idea, and I thought about it a lot myself but sadly there’s not a very clean solution with lightning. From what I can tell the only way to make this possible today with lightning would be to take custody of it upfront when the prism is created through some kind of escrow. But I don’t think that’s a great idea.

Although If you knew the recipients in the prism upfront I believe this would be possible with HODL invoices.