I believe you're talking about future perfect tense, and it seems to me that you do not need "had".
First, consider how you would convert a simpler sentence from present perfect to future perfect. For example, "She has seen the film." This means your sister saw the film (and completed the action) sometime before you said this sentence, and it's not particularly relevant when she saw it (as opposed to, say, "She saw the film last Tuesday.") Now consider how to convert this to future perfect. You should replace the verbs with the future perfect construction "will have [past tense verb of interest]". So, "She will have seen the film [by next Tuesday]." This means that by sometime before the time you're talking about, she completed watching the film (but perhaps she watched it before you said the sentence, and perhaps she will watch it between when you say the sentence and the future time you're talking about--either situation fits the sentence.)
Now we're adding "have to" (equivalent to "must") to the sentence. Consider what you would say if you were talking to your brother about taking your sister to see the movie now, so long as she has already seen the prequel. Probably something like, "(In order for me to take her today,) she must have already seen the movie" or "She has to have already seen the movie." (Note that the conditional verb you're talking about is actually that you will take her to see a movie if she has already seen the prequel--her seeing the prequel is not the conditional, but the condition.)
Using the same rules we used in our simpler sentence, the present perfect "She has to have already seen the movie," becomes "She will have to have already seen the movie."