Thanks Gerf's prompt response.
Your diagram is clear and proof my understanding should be correct.
The original thread was shown how to via an additional of relay to realise the opening and closing trunk lids via one button in cab. The proposed idea is to provide a constant 12v power to 85-86 and that's mean 87&30 will alway connected. In other words, 30&87a will never connect. Then, why still need connecting wiring to 87a?

 

In practical use 87a could be the power supply for an alarm system or any other function that needs power when the ignition is in the off position.

 

Noted. I know what you mentioned. Thanks for your patience.However, 30 in the original proposal is connecting to a switch but not a constant power. Even if ignition in a off position, 30-87a connected, device connected to 87a still doesn't work.
I'm not challenging the proposed wiring since it should be work for some members, but I want to clarify the logic before I start my DIY project.

 

In post 10 Mrbiggs mentions that they had to modify the front switch to make it a 2 way which makes sense because the rear switch can only be switching motor polarity to close the trunk but he doesn't mention how he did it or if the closing sequence final squeeze/clamp worked properly. I had a 96 ls400 that developed a problem with the sunroof control module just as I was about to sell it and didn't want to spend any money on it so I connected a fused 2 way momentary switch with a relay to the power wires so I could open and close it with a manual stop because the module was out of the equation.
I think you will find it simple once you begin the mod, I wouldn't do the mod because there is an open and close switch both existing in the trunk lid and if I have to open the trunk from inside so someone can get something out they can close it too...manually or with the close button.

 

Yes, I also read Nguyenazn's Post 23. Due to different model to his LS, mine is GS200t. I can't refer his photos as reference.
I also refer to the YouTube video in post 8. The proposed wiring is some differ to Shibumi1. First, he only connect 4 cable(but he still use a 5 pin relay &#128517. Two for 85-86 connect to the 12+ power which can be activated by remote(this is also my query, since while pressing the remote, it should stimulated both open and close signal, will it be jammed? i didn't study Audi's system). The other two cable from close switch connects to 30-87a. (Rationale).Anyway, I got the 5 pole relay and everything is ready. Just pending for action. Thanks for your kind advice. I will move on after figuring out the logic clearly. Because I afraid false wiring will harm the ECU.