Hi,
If this user order contents products from multiple user, can each vendor update their own order status?
Yes, they can.
If yes, when all the vendor have changed their own sub order to shipped, than the main order change the user order to shipped automatically?
Exactly !
If one vendor canceled their own sub order, and other vendor changed their sub order to shipped, what will be the user order be?
Because HikaShop 2.x do not authorize the multiple order status ; the main order status won't change until every sub orders are not all the same. But the admin can change the main order status (and it will affect every sub order).
Cancelling an order mean that the customer need to be refund ; so that part should be see directly with the store admin.
Regards,