We use a system called the cobra cabling system. It can be installed static to hold two stems together if they are already starting to split at the base or dynamic which allows the tree leads to still move independently while adding extra assistance if they are not split.
Tree Support and Protection can take different forms. This would be a cabling system. We also do bracing, which is often installing bolts where two trunks start. This could be done because a split has started or just for additional support.
Knowing if your plants need to be reinforced and how to do it is a matter for experienced professionals. The need for some bracing may be obvious, but if it is not clear how to go about it, then there may be harm to the tree or someone may easily get hurt in the process without the proper training and experience. There are tremendous forces involved and too much bracing, which does not allow for enough movement can be just as bad as too little bracing or bracing in the wrong places or too tight or too loose.
This is the kind of thing we want to avoid. And it often can be avoided, between bracing and proper pruning you can keep your trees around for a long time.
also called: tree cabling