you see my one
1. open your MySQL by HeidiSQL then go to world and open creature_template press on data
2. look for a vendor from the mneu then duplicate it make new entry for it and if you like cheng the modil as you like dont forget press post at last
3.open npc_vendor then add the item you like press post then rset the server
that is all
maybe i didn't explain well what i want.. in my example i create one custom vendor that sells 1xAlterac Manna Biscuit, but the point is i want that custom vendor show 20xAlterac Manna Biscuit by the same price, not just 1