Zap receipts only work if the zap request event contains all the necessary data, For regular zap requests the sample code is below, and just above it is the code for fetching zap receipts
https://github.com/abh3po/nostr-polls/blob/main/src%2Fcomponents%2FCommon%2FZaps%2Fzaps.tsx#L63
I've not done zap splits , but I think the way to do it is to divide the amount and create individual invoices to the participants.