Window in existing and new wall

[yoi65]

I am trying to place a window in an existing masonry (drawn in existing phase) and furring in a new construction phase. The window cuts through the masonry but not the furring. How do i get the window to cut thro' both.
Would it matter if the phases are changed.?
How about joining and locking masonry and furring, would that help?
Thanks for suggestions.

[d.stairmand]

You should be able to Join the Furring & the Wall together & the Opening Cut should transfer through to the Furring