As women have always known, the mother-in-law/daughter-in-law relationship is inherently a delicate one: it's only men, as Arnstein notes, who can (safely, acceptably) joke about mothers-in-law. And today's changing family configurations--with late marriages and career wives, much divorce and remarriage--make new demands all around. Using survey results, the commentary of experts, and her own practiced observations, Arnstein (Getting Along with Your Grown-Up Children, Brothers & Sisters/Sisters & Brothers) covers the ground capably: from the first wary meeting (when social and religious prejudices may surface disastrously) through the early married days (when Mom may be all too quick with recipes) and the arrival of children (when mother-in-law meddling is most resented) to the problem of maintaining grandparent/grandchild ties in blended families. Her survey showed, interestingly, ""no cultural or national distinctions between mothers who were possessive of their sons and those who were not."" Women with daughters were more comfortable as mothers-in-law than those without; and younger mothers-in-law, unsurprisingly too, fared better than older ones. But unresolved childhood problems may intervene in any situation: some daughters-in-law look for the mothering they missed; others act out old hostilities; all are apt to overreact out of insecurity. Arnstein's airing of jealousies, resentments, and plain misunderstandings could be beneficial (she rightly points out how a mistimed phone call can misfire). Her advice, though the next thing to obvious--mother and wife shouldn't force son to decide who comes first, each should respect the other's lifestyle and needs, etc.--may be just the sort of reinforcement that troubled women are seeking. No startling insights--but sensible and aware.