You can demo using the Split Payments and Pay Links extensions at https://demo.lnbits.com/ extension to do what you want. For production use your own LNBits install.

Also, if you want a more permanent solution without doing your own Lightning server / LNbits install let me now and I can set up an account on my install at https://lnb.bolverker.com . If needed we could do a quick video chat and you'd be good to go in minutes.