Why do the family of the questioner's husband see immoral dreams about her with their male siblings?

These dreams are of no consequence, and one should not pay them much heed, for they are either falsehoods or visions from Satan. Therefore, the person claiming to have had such a vision must be advised not to speak about it. If they persist, then the sin is upon them, along with the necessity of fearing Allah and adhering to the legal hijab (definition) in front of non-mahrams.