Is it possible to help a stepdaughter become pregnant if we look for legal advice?

Bad idea. Bad, bad, bad. You can call a family lawyer and ask; they'll usually give you a few minutes of free advice. Basically, by being a known sperm donor, they can come to you later for child support. And what do you do if you decide you don't like the way they are raising "your" kid? Or what if their marriage breaks up and she decides she doesn't want the child anymore and your wife decides she wants the baby, because it's "your" baby?

Further, you don't know that this is the husband's fertility problem. Has a doctor examined them both? Have they been trying for at least a year? It's entirely possible that his sperm is fine and she has blocked tubes or something.

But really, if they need a sperm donor, have them use someone from a sperm bank. Then they can get characteristics that they want, but no legal problems.

I realize that you have been a member of Y/A only since May 30, 2016, so perhaps you don't realize that we can go back and read your previous questions in your profile.

This new story today is a very interesting scenario, because 3 days ago, in the "Trying to Conceive" category, you said you were a female, and you told us you were trying to get pregnant for the 5th time; and 3 days ago, in the same category, you told us you & your boyfriend are trying to get pregnant by having sex every morning.

Now today, you claim that your wife wants you to be a sperm donor for your step-daughter. I think we have a new troll in the making.

If she is asking for a donation then you will have a hard time finding a doctor to help you. Anyone who did would risk being hauled up before the ethics committee and risk losing their license.

this is not a good situation at all. if she's asking for donated sperm that's one thing but still kind of weird. if your wife is asking for you to sleep with her that is just WRONG so say NO

Yeah, that never happened, just like all the other scenarios in your question history.