Help for Aimeos

Hi, I'm still evaluating if using aimeos could do my case or if i should start from scratch.
I mainly have two particular requirements, the first is that I have multiple stores, but the cart, the products and orders should be "unified" and it must be possible to order from multiple stores at once. But only the "owner" of the store can modify its products.
I would also like to disable the frontend, I only interest the json APIs.
Would it be possible to add custom attributes to the tables?

If you can point to the direction from which to start it would be appreciated.

Greetings, Nicolò

If you want to implement a real market place, you need the market place extension from the Aimeos company:
https://aimeos.com/extensions/#c1331

You only need the checkout confirm (a.k.a "thank you") and payment status update page in case you are using a payment provider that redirects back to the shop and/or notifies about payment status changes. The rest of the "default" routes can be disabled if you like.