Yes, however Amazon doesn't let you change the EAN for a similar product already existing on Amazon. Brand and manufacturer should not be a known brand who may already have an existing EAN. To post under your own brand you have to go through brand registration, which you cannot do with our codes because you need your own prefix. However you can post products under a brand name that has 3-4 letters as algorithms allow it without brand registry. If you are trying to create variations of existing products it will not work if the other variations have different code prefix, you will have to create a new product. See link above for our dedicated Amazon selling page.
This error can occur for multiple reasons. When you are trying to list an item with an existing brand that is registered on Amazon. When you are trying to add variations to an existing product with codes with a different prefix. The solution is to find a short brand name that is not registered, and that will not run into error 5665. Short 3-4 letter names usually work. Algorithms change often and recently for example "n/a" or "N/A", or brand names such as "Shir", "Hill", "Good", "Jea" or other 3 to 4 letter brand names seem to work but you need to try with your own name. You need to change the brand name until the error disappears.
The brand name is too complex, you need to go through brand registry to have your brand name approved. This is an Amazon specific process. The solution is to use a simpler brand name. algorithms change often and recently for example brand names such as "Shir", "Hill", "Good", "Jea" or other 3 to 4 letter brand names seem to work but you need to try with your own name.