Improved equipment patent

The customer has an existing device, so he contacts the staff of the original manufacturer (one of the shareholders) to improve it, without going through the original manufacturer directly. Of course, it is not illegal, but shareholders have the ability to upgrade the original equipment. In addition, as long as the other party does not produce and sell such equipment by itself, but only uses it or sells it for the original manufacturer, it does not constitute an infringement of the intellectual property rights of the manufacturer. Upgrading and improving other people's equipment, as long as the other party does not apply for a patent and does not enter the scope of patent protection, does not constitute infringement of intellectual property rights.