you can do this in 0xChat 

 multiple payments in one token?  

 When the client generates the zaps
, it would just lock half to one npub, and the other half to another (assuming 50/50 split)

So the client wallet would take X amount of ecash and request the mint to create new ecash tokens locked to the proper npubs, and then you just sent those along with your zap note. 
 

 The receiver could just look for ecash locked to its npub, and then claim it immediately and add it to a wallet. 
A couple of web based cashu wallets do this currently using nostr DMs 

 The @boardwalk guys with @bob and @gudnuf are sending huge zap splits with Cashu afaik.

A single payment is instant, could you just send n payments and that's it? Thinking of @PABLOF7z's new invention (notice how I avoid the name nutsack), you could send multiple note events with ecash and you should be good.

Can you explain the use case in more detail? 

 I'd you want to lock to npubs: You can lock as many tokens as you like to as many pubkeys as you like (there is a limit but it's large) with a single swap transaction to the mint.

The locked tokens are then just a bearer assets: send them to as many people as you've locked to. 

 Currently just holding a balance in cashu but paying out over lightining. The dream is nwc + cashu zaps for massive amd instant splits