Isn't it simply this: "We will buy when OBOS increases to -80.5 if MF is increasing at that time."
I'm not sure what the phrase "while OBOS remains above -92" adds. Obviously, if OBOS is -80.5, it's above -92.
Unless you are conveying that MF has to be increasing the entire time OBOS has been above -92...or unless you are conveying that MF has to have increased from where it was when OBOS was -92.