Transfer associated data to another DB

Question

Hi,

i need to transfer data from one SQlite3 database to another, preserving all the associated records.

For example, Person has many messages, each message has many attachments.

I need to transfer, say only "Person1" and "Person2" with all messages, belonging to them and with all attachments, belonging to each message.

I've heard about ATTACH syntax a little, but don't know, how to figure out this task in my case, using INSERT via SELECT from another db syntax ?