I see two courses for resolution:
1) PILs don't see Taylor until her parents either she's old enough to not take FIL seriously or until FIL stops (yes, that means MIL couldn't see her either) OR
2) Parents train Taylor how to understand these things that come out of FILs mouth are not true, which would be unfortunate but help her not to get upset. They'd step up the training when the PILs are due for a visit, "Imagine I'm FIL, and I tell you -- 'Taylor, we're going to Disneyland for a week!' you say, 'Not true, FIL' or look at Mom and Dad shaking their heads no at you because it's not true then go out to play" or something like that. Basically, what a PP stated about teaching the child that FIL is not being truthful so not to believe him then get upset when it turns out to be a lie. I've actually known an adult who pulled that on me, one of his peers (asked me if I wanted to go to a specific place, I said sure, then when we drove right past, I looked at him and he just gave me this mean-spirited grin and said he just wanted to mess with me when he asked me...I refused to hang out with him again after that -- I only did that day to be nice as he kept pestering me but, after that, I realized he was a super-butthead and I need no longer feel obligated to be nice to him).