we are lucky with my MIL and my parents - so far, they seem to understand and have been supportive.

It is one of my sisters that we are making very sure she does not get wind of what's up with our kids - even my parents have stated that it is important that my sister is kept in the dark with what's going on with my kids with regards to giftedness and their development because she is so competitive by nature that we are concerned she will attempt to hothouse her daughter or do something silly in her attempts to keep up with what our kids do naturally. She went on attack on my family a year ago anyway, so we have stopped talking which makes it easy for me to avoid her, and I have to purposely keep it vague with my other sister when I talk/email her so that she does not accidentally let something slip with my sister.