This is an amazing list thank you! I dug into them and it looks like there are even a few open questions about implementing this on the protocol level.

dillion

Has anyone ever come across a problem where they want to pay multiple recipients?

How To Pay A Split Bill Using The Lightning Network

https://thebitcoinmanual.com/articles/pay-split-bill-lightning-network/

Splits ⚡ Split bills with your friends, instantly

https://www.checksplits.com

https://github.com/verbiricha/splits

Going Dutch - A lightning based splitting the bill service

https://goingdutch.pm

With Going Dutch, each split is for an equal amount.

bitcoin

Pay one invoice to multiple recipients?

> Has anyone ever come across a problem where they want to pay multiple recipients?

*How To Pay A Split Bill Using The Lightning Network*
https://thebitcoinmanual.com/articles/pay-split-bill-lightning-network/

*Splits ⚡ Split bills with your friends, instantly*
https://stacker.news/items/15645
https://www.checksplits.com
https://github.com/verbiricha/splits

*Going Dutch - A lightning based splitting the bill service*
https://stacker.news/items/6144
https://goingdutch.pm

With Going Dutch, each split is for an equal amount.