Is it okay to install the wiring aid by simply replacing the lenses?

Is installing blind spot monitoring (line merging assistance) enough to replace the original car lenses.

No, the rearview mirror lenses only serve to display warning lights. If you want to install a lane change assist system on the vehicle, you need to follow the following steps:

Install the corresponding radar or car camera:

The lane merging auxiliary system needs to collect data around the vehicle for analysis and processing. If using a camera, it needs to be installed at the front and rear positions of the vehicle, so that the road conditions around the vehicle can be clearly seen. As the mainstream technology currently uses millimeter wave radar for detection, camera based blind spot monitoring (parallel line assistance) will not be mentioned below; If using radar, it needs to be installed at the rear of the vehicle in order to more accurately detect surrounding obstacles and vehicles. When the millimeter wave radar sensor detects obstacles or vehicles, it will transmit data to the control module.

Install the corresponding control module:

(Some systems will integrate control modules into sensors). The lane merging auxiliary system needs to transmit the collected data to the control module for processing, and control the vehicle's driving direction and speed based on the processing results. Therefore, it is necessary to install corresponding control modules to achieve this process.

Replace the rearview mirror:

In order to facilitate the driver's observation of the surroundings of the vehicle, some lane changing assistance systems need to be equipped with corresponding rearview mirrors. Generally speaking, the lane change assist system warning light will be displayed on the rearview mirror lens, and some models will display the warning light on the interior triangle window (such as Nissan and Haval models) or inside the rearview mirror housing (such as Audi models).

In short, installing a parallel auxiliary system requires multiple tasks that need to be carried out by professionals. If you want the vehicle to have this feature, it is recommended to consult and operate it with a professional.