I had hoped

by soaking it very gently in a warm bath of water, the soluble thread would dissolve and leave enough of the feather marking to save me doing it all over again. As you can see the marking instantly has started to wash out even without moving the water at all.
The water went purple from the black marker after a ten minute soak, (remember this marker has been in this top for well over a year). So I have retrieved all the feathers and I think they'll be fine to glue to the back of the newly marked top. I'm not so sure about the big corner ones, they may have distorted as I lifted them with the weight of water. Time will tell.
Today's quilting effort is to go to the local carpet shop and beg a cardboard roll or two for the Giant Feathered Star and Exquisite Feathers. I can't send either wrapped on a roll but at least I can store them crease free until it's time to post them off.