“Have you known” or “Did you know”?

Question

First of all, I know it has been mentioned before but I'm not sure which is correct. I've been learning about the Past Simple and the Past Perfect and if I've understood correctly, well, in high level:

Past Simple - Occur in the past (in a specific time) and finished.

Past Perfect - Occur in the past, certainly continues to the present, and maybe continue in the future.

This is correct?

--The main Question--

Have you known that Harald has a very bad disease?

1. So, Here someone explained that, "Did you see this?" is for events that happened in the past but finished/passed (you can't see it anymore).
   However, use "Have you seen this.." if you missed that, you still can see that. Is this correct?

So I thought why not, if I ask someone: Have you known that she's been married? (Did you hear that she's been married? if not, now you can still know about this, because she's still married. Related to the above explanation) and it looks like I ask “Have you known...” from the past until now (present perfect), so why is this incorrect?

Well, Here I found that example about Harald, and they commented that you can never say "Have you known...?" only “Did you know?” but they didn't explain why the former was grammatically incorrect.

2. Actually, I want to understand what is correct, and why in context to past simple and present perfect (grammatically) and how can I use both of them correctly in questions?

Answer 1

Regarding:

Have you known that Harald has a very bad disease?

I think most people would say:

Did you know that Harald has a very bad disease?

because you are asking what someone knew at the present time. Unlike seeing (where you see something at some point in time), you generally don't "unknow" some piece of information.

However, you can explicitly refer to a time progression like this:

How long have you known that Harald has a very bad disease?