Is it permissible to ease the wearing of the niqab in front of relatives to avoid problems and displeasing the family?

It is obligatory for you to obey your husband regarding wearing the niqab. For, despite the difference of opinion on its obligation, it is nonetheless incumbent upon the wife to obey her husband if he commands her to wear it. Your husband's brothers and your sisters' husbands are not mahrams, and their ruling is like that of strangers concerning the impermissibility of revealing your adornment to them. Your fear of angering your family or your husband's family is not an excuse that permits you to disobey your husband, for obedience to the husband in what is good takes precedence over obedience to parents.