Can I ship goods from multiple wholesalers in one container?
Indeed. You can either ask your Yiwu agent to coordinate this for you or make sure that you buy according to FOB (Free on Board) terms from each supplier.
You should then instruct each one to order transportation to your freight forwarders local office in Shanghai.
From here, they can pack all the goods in one container, and delivery it according to DAP (Delivered at Place) or DDP (Delivery Duty Paid) terms.