[blutorange]

I do not understand the confusion as to が and を, and what this has to do with relative clauses: が marks the noun that is performing the verb action ("subject"), を the noun the verb action is being done to ("object"). That is, when used with 知る, が marks the person who knows something and を the fact this person knows.
Whether in relative sentences or not, 私を知るwhich obviously means "someone knows 'I'", which is not what we want to say. And it is a general rule that 誰 cannot be used with は, but needs が. This has nothing to do with 知る.
Similarly, 私を分かる doesn't mean "I understand" either. 分かる could be said to be an "exception" (as for が), but as for 知る and many other verbs, they behave as expected with が and を.

Your sentences seem to be alright.