I faced a problem like yours by creating an invisible form in the default datasession, with a cmdButton in it, and a public variable .

The frmInvisible.cmdButton.click() code was something like:
SELECT "MyPublicTable"
SCATTER NAME oTemp

Then, from the form in the private datasession, in a do while / enddo loop put a code like this:

frmInvisible.cmdButton.click()
SELECT "MyPrivateTable"
APPEND BLANK
GATHER NAME oTemp

The code above is simplified, because there was a part of it testing the record number and so on, but I think you got the idea.