re: Help pls! How do I secure a diamante brooch to extra large gumpaste bows?

I am assuming the brooches are real, heavy metal brooches. If so, you will need someway to secure that thing to the cake. Without seeing it, my recommendation would be a wooden skewer attached to the back of the brooch with a healthy dose of hot glue. Stick that into your cake and build the bow around it. The customer can even remove the hot glue afterwards and keep using it.

As far as transporting big bow loops, I carry my cakes assembled with the bows in place. I will carry 3-4 extra loops in case of breakage, but honestly I rarely get any broken loops on the trip. Hope this helps!