You might also consider weight lifting to make the plants stronger. Add a piece of wire with a weight of some sort so it just starts to pull down on the branch, then continue adding more weight as the branch starts to be able to support it. I also do something i call flex training on rubbery branches....though hmmm not sure how to explain the technique. Grasp rubbery branch between your thumb middle finger and forefinger. Manipulate the branch over your forefinger so it bends heavily(almost 90 degrees) over your forefinger, and then slide your fingers(while bending) to the next node. The plant will be bendy for the day, but after a day or two of doing this it will increase rigidity alot. I also use this on tiny seedlings(but without the slide up the branch) to increase main trunk rigidity early so they dont get floppy in minimal air flow. Gosh i hope that makes sense!! I do have some work to do on some rubbery plants, so i will take some pics to show examples.