It's been a long time, but I used to do transfer work on a variety of fabrics... depending on how large the fabric is, securing it to the edge of a table with painters tape (try a small section first to ensure no residue is left on the fabric) or wrapping it around cardboard and securing it to the back with pins has helped me in the past. Admittedly, I'm not sure how y'all are doing all of this but would be interested to watch some time. :)