A person's wife is permissible to him, yet the daughter of his wife is forbidden to him. Should it not stand to reason a fortiori (by kal vachomer) that the daughter of a married woman, who (the married woman) is herself forbidden to him, should be forbidden to him as well?
This exact question is asked in the first perek of Derech Eretz Rabba. As recounted in another answer essentially the response is that this Kal V'Chomer would be oker (uproot) something from the torah, in this case the possibility of a Kohen Gadol marrying and thereby having children, and we do not allow for kal v'chomers which uproot something from the torah (and Rabbi Gamliel excommunicated the asker).
The Nachalat Yaakov ad loc cites the Yalkut (Shimoni?) in Parshat Emor as having a similar text. He further cites the sefer Zayit Ra'anan who explains the question and answer as mentioned above but posits a flaw in the answer by suggesting that the Kohen Gadol could marry an orphan. Zayit Ra'anan answers that this wouldn't help since the mother was forbidden before she died and thus the prohibition would have already taken effect on the daughter. See the continuation of the discussion in the Nachalat Yaakov.
Halochos Gedolos - Halachos Arayos brings that this question was asked by Yosi ben Tadai Ish Teveria to Rabbi Gamliel. Rabbi Gamliel answered him that it would be impossible for a Kohain Gadol to ever get married. The Mishne Halachos there explains that by the same logic a Kohain Gadol would be unable to marry anyone's daughter, as every woman with a daughter is someone the Kohain Gadol cannot marry (a married woman, divorcee, or widow). This is impossible as the Torah clearly says regarding the Kohain כי אם בתולה מעמיו יקח אשה.
Talmud Makkos 5b (and throughout Shas)
1) Ain Mazhirin min HaDin.
2) Ain Onshin min HaDin.
We may not deduce a Torah prohibition warning, or a punishment for a Torah prohibition from a Kal V'Chomer argument. Rather, the Torah must say it, in order to qualify it for a punishment.
But, that's only good for the punishment aspect. (TY @Yishai) We still have the problem that the daughter of a married woman seems simply forbidden by the Kal V'chomer?:
1) The permitted wife causes many otherwise allowed relationships between the husband's and wife's relatives to become forbidden. The other man's wife does not. Therefore, maybe that is why the Torah was strict by a man's wife's daughter yet not strict concerning another man's wife's daughter?
2) Before a man married his wife, he could have married her daughter. However, the other man's wife's daughter never had a change in status. Perhaps the change in status is the source of the Torah prohibition which would not apply logically to the married woman's daughter?
3) If this Kal V'chomer were true, then the original "permitted wife" in the formula was not in fact permitted (since she herself is some married woman's daughter). Therefore the Kal V'chomer doesn't start.
In order to disprove this (attempted) logical deduction, we must give a reason why the daughter of the man's wife is more strict than the daughter of a different married woman. I think the reason is obvious: the daughter of a man's wife has a kind of familial relationship with the man that the daughter of a random married woman does not have with the man. Therefore, the daughter of the man's wife is considered a type of incestuous relationship.
If the reason a man's wife's daughter was prohibited was because the girl's mother is married, then your logic would follow. But that would be a very strange reason to prohibit someone from getting married (the majority of girls' mothers are married).