Scrabble Flash Competition in Progress

The girls received a Scrabble Flash game for Christmas.  We recently opened it and cannot stop playing it now.  There are only five tiles, so it's a good level for the girls.  It's a lot of fun as the girls can spell a lot of works that are three, four or five letters.
Usually we play one parent and one child teams.  The blond twin has been on the last two winning teams, so she's sure she's the lucky charm.  At the end of tonight's game, she said, "I want to be with Sissy next time so she'll win."
It's a sweet thought, but it presents several problems.  What if the two of them don't win the game?  The girls will feel badly and we'll feel like we took advantage of them.  After all, shouldn't two adults be able to beat two 7-year-olds at Scrabble Flash?
The harder problem is what happens if they do win.  Do we really want to put ourselves in a position to be beaten at Scrabble Flash by our children?