1. Cousin S could be possibly Sherry. Or it could be that Corporation S, Ada referred to in Separate Ways (I don't know if "S" Pharmaceuticals is even consider canon anymore or it was a translation issue or they just switched it to Tricell).
2. Mother. I'm completely in the dark on this matter. I can only assume the word 'mother' is being used in terms of relation to 'uncle' in that mother is someone who is watching her brother. Basically someone close to the president in terms of position to be close enough to make sure he is taken out. Perhaps it's Harper?
3. Family. I think it may be referring to the companies within the GPC and here is why I say that despite Jessica's report saying the GPC is not evi;/corrupt, hogwash in my opinion, etc. Didn't the GPC cover up or know that Umbrella was involved in their B.O.W. dealings and decided to give them up in order to not meet the same fate? Also Excella Gionne was a GPC officer and Tricell is obviously a member of the GPC. I don't think the entire GPC is corrupt/evil but there are elements within the consortium that are up to no good. I think perhaps the family may be referring to this. The only issue with this is it seems this ties into the U.S. Government's involvement more directly then the GPC itself.