I just remembered, i sometimes use printed border designs. Borders Made Easy. they have delicate tape on the edges of the paper to hold it in place, you stitch the design and then pull the paper away. Some a bit tedious but it looks great when done. Just another thought...

Do not use pencil, frixion pens, or yellow chalk markers. These things are all notorious for not washing out.

I would use something formulated *specifically* for quilting and washing out. The air-erasable pens Dunster mentioned are what I use.