Hi Shirley, that thread is used in the bobbin, but I would ask your embroidery machine dealer to configure a new bobbin case to handle that lightweight type of thread. What weight of thread are you using in the needle? If you want to use that thread topside you'll have some issues. I use 60wt top and bottom when embroidering FSL butterflies and doilies. 90 wt is too thin for topside.
Good luck, update me when you've finished your project. You can also do a live chat with Brother regarding that weight of thread.