Good question and I don’t know exactly but I believe instead of Nostrgram sending a zap invoice request to only the note author’s wallet, it sends invoice requests to the address of each tagged npub. I’m not sure, though, what happens when the paying wallet receives multiple invoices at once to be paid. Like if a note tagged 50 people and I clicked to pay them all 21 sats, what would my wallet do when it received 50 invoices back to be paid? Will be interesting to try, maybe with a test wallet at first and very small amounts 😂