For the traditional Chinese, all kids are 1 years old when they give born.
And the kids pass a chinese new year, their age will add 1 year.
Therefore, for my case, I born in January. When I was 1 months old (Chinese New Year in Feb), I was already 2 years old.....
It is because in the old chinese, there are a high % of babies can not growth up (esp. in the first few months of baby stage due to sickness). Therefore, they count 虛齡 (esp. for kids) so that it indicates that the kids have already pass the 'high risk' ages and can growth up healthy.
I think you have a bad relationship with your 99 so that you think that all the things she did is not good for your kids. If you don't like the wishes (from old chinese), then you can just directly tell your 99 that you don't believe those traditions and won't follow them (even this will harm your kids).