Hello,
Dimensions uses their own brand of floss for their products so the only way to get more floss for their kits is to get it from them. Here is their contact information:
https://www.simplicity.com/contactus
Monday to Friday
8:00 AM to 4:30 PM CT
1-(800)-794-5866
Just let them know what items you need for their kit(s) and they should be able to send it out to you :)
~Kristi @ ECS