Yes, you can sell other brands with your Amazon Vendor account, but you need to establish separate agreements with those brands and go through the approval process for each one. Your account manager can provide more guidance on this. if you need any help ask here.
The brand that i want to sell it`s not big brand with big name.
We found that brand at our supplier so when we try to add in vendor wee have clear way.
Why we need separate agreements with new brand?
I believe that recently, Amazon changed and strictened the rules when discontinuing the original Vendor Express program.
The Vendor Central is mainly aimed at highly demanded brands with a strong presence and their manufacturers. However, if you have an account manager, you should reach out to them and inquire whether you can also sell other brands.
These decisions are usually made on a case by case basis.