Hehehe... I have one of those MILs!!! I am feeling your pain. After a while we become professionals at deep breathing and counting backwards from ten.

We have chosen family names as middle names for our kids... we are only planning to have 3 (hopefully), so either way someone is going to miss out. I agree that it is your choice and nobody elses. And she should feel very special to have scoredOscars middle name.
Some parents just don't know when to butt out... its a good lesson for us in 'what not to do when our kids grow up'.
Good luck and stick to your guns!