I've been to Japan a couple of time before and my YUL friend (I'll call her Patty) has not. We're both non-Japanese and I have friends in Fukuoka that I'd like Patty to meet because we are all huge fans of a music icon. My Japanese friend (Yoshi) and his brother (Kenji) will pick us up, hang out sightseeing, karaoking and then take us to their parents' home where everyone is and have a big dinner there with his entire family (wives, kids, aunt and parents). This would make it my 3rd time.

When we get to their parents' house, would it be my job to introduce Patty to the rest of the family? Or do I leave that to Yoshi? Yoshi also happens to be the only one in the family that can understand English best.

At the dinner table, I'm assuming that Patty will sit at one of the table ends with Yoshi and Kenji beside her left and right. And myself, I'll probably be in between Kenji and another family member. Is that right?

Here's another vote for jib71's sage words.
It sounds to me like you're imagining that a minor molehill is going to be a snow peaked mountain.

Ok I'm sorry everyone about that question. Ya I guess I was too observant. I now realize it's silly and feel stupid about it. Let's all have a good laugh at me and move on.

Oh don't worry!

I have plenty of family members who feel ill with anxiety imagining scenarios even more complicated than yours when faced with meeting their counterparts in Spain, England or Japan.

My view is that if you are going to offend someone by sitting at the wrong table place or by introducing someone out of turn, that person would have found some other way to get peeved off with you anyway.

Things have come a long way in Japan since Izanami committed the terrible gaff of being the first to speak at the country's first wedding.

Once the beer and nihonshu start flowing, people won't worry so much about etiquette. Be sure to pour for whoever pours for you and they'll be very happy. Soon, they'll all want to sit next to your lady friend and pour for her anyway. Have fun.

Kyushu=Shochu.....

Unless you like warm Sake very much like my brother does, Q!

Sanosuke!