@idontknowwhattoput Thanks for letting me know! I am not aware of an official way you can mount both of the pieces without screwing, but you might be able to figure out a more DIY solution. It’s possible you could super glue the pieces together, but of course, this is completely up to you, and not something I have personally seeing yet that is. If you’re willing to get it a try, I recommend it! It’s worth getting input from friends and family too if possible. Some people may be more creative than myself. 
When it comes to the motion detection and where you pointed out where you are getting alerts of motion from in comparison to where you need it, it’s simply because the motion where you need it is very far down and can be out of sight on the camera at first, which causes a delay or loss of motion. In addition, since cars are more frequently coming and leaving than people, you may have a concern with your Motion Frequency. If you have the frequency set to standard, this could cause the camera to have more down time in between motion events. I recommend putting it to frequency to see if you get more of the people you want to see coming and going, on video.
Lastly, I am curious, for the Min to Max slider within your Motion Zones, where do you have these set at? I would love to see where this is set at to see where your sensitivity is at! This can help us figure out a way around this concern further, and good information for me to know. Ultimately, I feel the view of the camera may be to blame in this situation. I’ve had a situation where a neighbor that had two white poles in front of the view of her place were throwing off the motion detection, and she continuously got alerts of the cars in front of her home in between these two poles, but would miss her coming and going. Once she had it face a more open view without these poles, her concern went away. In the event you can conjure up a good DIY solution for your situation, we might need to look into relocating where the Doorbell is faced! 
P.S., I’m out on the weekends, so I look forward to your response on Monday. Thanks neighbor!