Does it cause me any hardship if my brother's wife is unable to observe complete hijab in front of me, and what is incumbent upon me to do?

It is not permissible for a wife to live with her husband's brother in a single dwelling with shared facilities. Al-Mawardi said: "If the house has only one room such that it is impossible for one of them not to see the other, then it is not permissible for her to live with him in it, even if she is accompanied by a mahram or trustworthy women, because the eye cannot be protected once it is let loose." If the dwelling has shared facilities and is prone to suspicious khalwa (private seclusion) and mixing, then it is forbidden. However, if there is an independent section within the dwelling that ensures safety from khalwa and mixing, then the brother's wife must maintain her hijab, and the brother must lower his gaze.