【My sister-in-law,and then,I will directly call her sister】- I guess you would like to say: "My sister-in-law that I just want to call her, my sister"

It depends on what you mean by correct. I think it is grammatically correct, so that the meaning would be communicated, but it does sound like an odd, or convoluted way to say it. I am guessing that the meaning of directly is immediately, or very soon. If that is true it would be odd to say that one person, then the other will call a third person directly, because that second person will obviously have to wait until the first person is done calling-- so it would not be directly. Also it brings up the question of why the first person does not just hand the phone to the second person who wants to talk with the sister. That is what I would expect if the speaker and the sister-in-law were in the same place. If they were not in the same place, how would they coordinate the calls so that the sister-in-law would call first?

I have got the correct way to express this sentence.Thank you ♪

Sure,I'm sorry for I haven't express clear.我想表达的是，在我聊到我的嫂子的时候，我不想用嫂子称呼她，我想直接称呼她为姐姐，怎么样跟对方说这句话，比如：“接下来，我就直接用姐姐来称呼他”。And thanks for you answer.

Could you please "add details" with the sentence in 中文？ As it stands, the sentence has improper punctuation, and even with the punctuation corrected the meaning is completely different from what you expressed in your comments.