I don't know what to do with all the leftover seed. I tried to give some to my Gouldian, but he is not interested (he mainly goes for millet, no veggies or eggs...... another challenge to deal with)

Should I buy niger seeds for my canary and use very little of the canary seed mix or should I insist on giving the mix? BTW the mix was given to me by the breeder.
Also, I was at the pet store today..... no niger seeds. Can I give my canary niger seeds sold for the wild birds?..... I have three feeders in my backyard.
Thanks