Outside plants to close together ???

You may have to get rather creative with a roll of twine. You can use bamboo or some other lightweight stick, horizontally up inside the plant. Tie branches to the stick on both sides of the plant to help keep the stick in place. Then you can run other lines from the stick to more branches. You can tie the stick to the main trunk for added stability and even downwards to resist any upward pull if you are trying to pull branches down. It can look a bit like a sailing galleon with lines everywhere but it might be easier than trying to tie to stakes driven into the ground.

You can train them away from each other. Use low stress training, high stress training, SCrog, or trellising to keep them separated and sorted. I hope this helps. Good luck!