This is possible to do, but depending on your comfort level with QuickBase you may want to get a developer to help you.
When you make a button to copy in the children records from a specific parent to the parent you are sitting on the URL looks like this
"javascript:void(copyMasterDetailButtonHandler('&sourceRID=63&destrid=" & [Record ID#] & "', 'bfv72ften'))"
In he example above, the record ID 63 is the Project from which the children will always be copied.
So, you could make that field and then modify it to substitute in the Parent which has the children you want to copy in. You could have a table with one record ID in it and a field to hold the value of the Parent record that you want to copy from. Then make a URL formula button which the user would click to update that record with the value of the record ID they are sitting on as a source parent.
The value on that field would be then carried down to all the Parent records in a lookup called pergaps [Source Record ID#]
That URL formuakl would them be modified to read
"javascript:void(copyMasterDetailButtonHandler('&sourceRID=" & totext([source record id#]" & "&destrid=" & [Record ID#] & "', 'bfv72ften'))"
Then they would go to the target parent and click the Copy button and the children form the identified source would be copied to the child. I would have a field on the target parent show to let the user know information about which parent's children will be copied in.
There are a few steps involved to make that work and you can either work though any issues that you encounter, or else contact me via the information in my profile if you want me to set this up for you.
