How big and what type of container are they in now? Most melons and squash have spreading root systems with a much smaller tap root. If you can put it in a larger container, it will buy some time. How long til you're frost free? They will have a better chance in individual containers. In a pinch, you could use a large coffee can with the plastic lid becoming a new bottom. Cut the side of the can all the way down and tie it shut with wire or strong twine. Then when U put it out, just remove the bottom, cut the twine, and slide the can off the top. With care, you can move some big
plants this way. I've also made square boxes out of scrap wood (not plywood or other glued wood products) with large gaps between the boards and on bottom, at least a couple inches worth, and wrapped the box with plastic. Then I peel off the plastic and
plant the whole box, letting it rot.
Rick