No.
You're not reading too much into it.
I mean the following statement in the best possible way:
When they put their minds to it, the female can be so dirty-minded in such a sexually creative way as to go far beyond any concept yet remotely perceived by the male. The 'weaker sex' my ass. They know exactly what they're doing and it's phucking awesome to behold.
1.) IMO Your stepdaughter wants to know if she's desirable to you. But there's something else that is fishy. Its obviously an act, wearing more when mom is there and less when she's not. You see it and she knows you see it and wants you to see it.
2.) You assume the daughter will be in trouble with her mom if she finds out.
Or is it a plan by both because they have talked secretly about you and their desires for you and decided they should work together to have you rather than something happen and they both lose you?
3.) If you DO NOT tell her mother, then your stepdaughter knows she is desirable to you and will no doubt take it to the next level, like ..oops.. losing the towel or ..oops..can't find my sports bra.. then after that...
4.) If you DO tell her mother and there is no plan involving both of them, then your stepdaughter will get her ass chewed by her mother, you'll gain your stepdaughter's undying enmity as a result, not to mention that your wife will probably always question your real motives in your relationship with her daughter thereafter.
5.) Or if you spend too much spare time reading the posts here and you have become a dirty boy like the rest of us who post here, you'll say 'fuck it' and stop trying to figure it out and just enjoy and do your best to let it play itself out, hopefully hot. Then, if these women are as naughty as I think they might be, you'll be fucking both of them together and separately with each others knowledge and as much as you want.
I kinda think #1 is probably true.
I think #4 is the worst possible scenario and should avoided at all costs.
I think #5 is a pipe dream, but it kinda made my dick hard just typing it and I deserve something in return after typing all this crazy bullshit for the last hour.
She's clearly angling for a beef injection from stepdaddy.
Maybe she's testing you? One false move, and your life could be over. I say do nothing. Enjoy the show, and let her make all the effort. If you make any sort of move yourself, it could easily explode in your face.
The little whore is trying to get you excited. Show her your cock.
I had a similar situation with a 24 year old stepdaughter who was blatant about coming out of the shower nude and exposing her self to me. She would always act like she was surprised and that it was an accident, but it was happening so often. I finally confronted her and our conversation became very charged and erotic. Needless to say, in light of the fact that her mother and I were on the verge of a divorce we ended up in the most intense sexual relationship I have ever had. A 48 year old man with a sexy 24 year old. Wow!