Hi, as I delete the julia data by mistake, I created another mtg including the julia information, which is mtg 15 16 17 and follow the steps. However, when I came to step 128, i found something different from the guide. The sample pic shows the correct address matched with mtg15 (should be mtg-01, but I recreate it into mtg15) ->pitch 12. However, I don't know why my address shows something I have never seen before. Also, when I click on the details, I can see that it was connected with mtg 15 and pitch 12...Need help, THANKS!!!

It sounds like you were correctly compensating for the deleted record, but you're right, the Address field is very weird. Not sure how you got that. I think you made a mistake when you created the Address field. I suggest you delete the Address field and recreate it again by going to Setup > Object Manager > Meeting Attendance > Fields & Relationships and delete Address and click New and then follow Steps 104-116 carefully.