to the best of my knowledge, no one has said anything about ob1 not knowing about leia. hes the one that tells luke that she is his sister, for goodness sakes! Anakin doesnt know he has a daughter until EPVI, and he may not even know he has a son until the time b/w EPIV and EPV;thats not really clear to me yet. Either way, ob1 and padme seem to be the only one that know about them both. unless yoda is the one that told ben about leia("no, there is another"😉 obi-wan probably knows, and yodas comment about another is just because ben doesnt think leia has the power...
I personally think he does. How GL will explain the reason obi-wan tells yoda that luke was their only hope, remains to be seen. GL is a good story teller, but even they make mistakes. There COULD be a very good reason GL put that in the script, and he has it all planned out somehow, but I haven't thought of any explainations yet.
the whole truth depending on ones point of view is not something obiwan came up with himself. if you listen carefully in episode I, qui-gon says the same thing to obiwan, reguarding anakin being the chosen one, if i remember. thats half of why i question the whole explaination of anakins parentage. seems like foreshadowing to me