A new Dutch study shows that the children of lesbian couples are just as happy and healthy as kids raised by heterosexual couples.  The findings mirror what large numbers of American studies have also shown: "Children do well in loving families, regardless of whether there are two moms or a mom and a dad involved."

Even more interesting is that - perhaps not so surprisingly - lesbian biological mothers show significantly more satisfaction with their partners as co-parents than do heterosexual mothers. The partners of lesbian biological mothers, according to the study's findings, "are more committed as parents than are heterosexual fathers - that is, they display a higher level of satisfaction with their partner as co-parent and spend more time on child care and less on employment."  Together, two moms heading up one family make more time to spend with their kids, and their kids are happier for it.  If that's not the best argument to add another wife to the family, I don't know what is. 

Bottome line: all you need is love.