16 businesses in one building share a checkout stand and all have separate square business accounts.

[chellestucks]

We have a small storefront where 14 small businesses rent very small space and checkout at one checkout stand. However each business is separate and has their own square account so if customers purchase something from 5 different vendors, I have to run their card 5 times through 5 different square readers. It is time consuming and upsetting at times for multiple reasons. We would like to set up it up so that each business can link accounts in a way that the business is separate, but the customer's card is only run once. 

[Donnie-M]

@chellestucks This is a hairy animal to give a haircut.  The problem you have here is more of an accounting problem.  All of the money on a transaction has to go into 1 bank account per location.  There is no way on square to have money in one transaction split out to different square accounts.

I personally would set up the different businesses as vendors and you have 1 square account.  It would be up to you to set up items for each vendor and account for the sales at the end of each day.  You would then get paid for the credit card transactions and in turn pay the vendors on the back end less any fees or charges.  I would talk to your accountant about the best way to set this up as this is a very unique situation.

The only other possibility would be to sell some type of certificate and use it as an alternate tender and each vendor trades it back to you for the cash etc.