DAA to DAd

I've been playing the MD since early June.  I bought the DAd (sorry if I write those cases wrong) kind.  I am happy playing it.  After buying it, my parents decided to buy one, too.  However, they didn't know what they wanted and ended up with one in DAA.  I wanted to help them learn, meaning we would practice together, but it is difficult as we don't have the same tuning.

Can the top A string just be tuned up to d or is it too thick?