Thanks @pfaffman ,
You can share more:
If there are 7000 topics in discourse2.com, then when I move 3000 topics from discourse1.com to discourse2.com, the 7000 topics in discourse2.com will not be deleted?
Then discourse2.com will have 7000+ 3000 topics = 10,000 topics?
I’m worried, my 7000 topics at discourse2.com will be deleted.