TinyHammies, the Burgess dwarf mix already has a fair amount of canary seed already in it, so adding more might just make it into a large amount of millet food. It also has loads of grass pellets which usually never get touched. I always use the other Burgess mix, the Syrian one. It does have died banana pieces in it though but these are very easy to see and remove. If you bought the Syrian version, you could then buy a 1kg bag of Canary seed mix from any good pet shop and add the whole bag to the Burgess mix. This would create a really good variety of seeds, grains and also poultry biscuits, which the Syrian version has in it.
The dried banana are the only pieces you need to remove from the Syrian version as Chinese can`t have high natural sugars. Banana is a fruit.
The rest of the mix is very good and doesn`t require anything else to be removed. It also contains mealworms but you could add more in if you wanted to. This is what I would be feeding any dwarf hamster.