Add a second parent.

I am trying to add my spouse to our children's account so that we both can work together with our kid's summer learning. I cannot figure out how to do that.  I did see that others had the same question, and when my wife attempted to add herself as another parent, the program said that only one parent could be connected to a child for privacy purposes.  It makes it seem like Khan Acadamy does not approve of two parent households, but I'm sure that isn't true - is it?