Is it permissible to marry the son of the deceased husband's brother, who is married to the daughter of the deceased husband?

Prohibition due to affinity is confined to four categories: wives' mothers and grandmothers, however high; wives' daughters and their daughters and their sons' daughters, however low; sons' wives and sons' sons' wives, however low; and fathers' wives and grandfathers' wives, however high. Based on this, there is no prohibited kinship between the questioner and her husband's nephew, which makes the marriage valid. It is also permissible for the husband to be married concurrently to the questioner and his former wife's daughter, as long as the daughter is not her own.