Wedding Crashers

Well I haven't seen the movie, but I did hear that one of the first rules of wedding crashing is to stay away from the bride and groom.
Rules?

Unfortunately our wedding crasher had obviously not seen the movie or perhaps she just failed to follow the rules as she came up to me numerous times and "welcomed me to the family".

(background: she (let's call her Mega-ho) received an invitation to our reception held at a later date but came to the wedding anyway - she knew when/where the wedding was because her parents were invited there. Mega-ho's sister confronted my husband to inquire why Mega-ho had not been invited and the answer that apparently the sister understood was because of "who she had become". Regardless Mega-ho is constantly drunk and not someone that is fun to chat with her alcohol mixed with horrible cigarette smoke breath)

So quite a bit has happened on this front. And to make a long story short, my husband's family and her family are at a mini war. I mean it's not a war, but I can't think of a better word. There was a long letter sent from her parents with little jabs and stabs.
As my husbands family discussed these issues, I sat quietly and listened. I was to be at the discussion because I am part of the family yet obviously don't have much to say as I lack the history that they all have.
But I can comment on the letter and my favorite part was where they state that Mega-ho was not at fault because she was under quite a bit of stress from work and did not read the invitation, but instead just sent in her reply.
So in essence she is dumb I suppose.

Two more points to her stupidity/ignorance and why she bothers me:
1. She tried to kick one of MY guests out of their seat as she didn't have one.
2. Two weeks after the wedding we went to another wedding (where she WAS invited) and came sat at our table and eventually was kicked out because there were no more seats and had to go to her GIVEN seat. HELLO? IS SHE DUMB?