Don't steal my thunder.
The number one rule of any wedding is clear: If you aren't the one getting married, then nothing is about you. Don't wear white or anything that'll take the attention off the bride, don't propose, don't announce a pregnancy to the whole wedding – you get the idea. This is the bride's special day, so get your own! This woman either didn't know the number one rule or didn't care.
Wow, there are no words for this act. Have you any decency? Is your niece so special that you can't wait for a different day to celebrate her birthday? Or at least wait until you leave the wedding venue? We will guess that the answer is no to both of those. She seemed to be trying to steal the bride's thunder and party.
