Great story and your cousin does look very ticklish on her feet. You said she has kids is she married or does she have a boyfriend? Maybe she really likes being tickled since she did not get mad at you and says its all in good fun. You might tell her you like tickling her and that you would like to tie her up sometime and tickle her and see what she says. That way she really could not get away from you tickling her feet. Its just a suggestion but if I were you I would talk to her about it. If you do let us know how it goes.
Glad you like the story guys...but I think I'll keep it to casual tickling! LOL! I'm prettysure that she might be a "bit" weirded out by mentioning tying her down!