Freeze Panes

Hey guys - quick question:

I've got a sheet with two different sets of column headers. my column headers in row 4-5 service my summary table in rows 6 - 33. Then I have a new set of column headers in row 34-35 that service the rest of the sheet. I need to freeze panes on row 35, but only when row 35 reaches the "top" of the window.

I've tried doing just a general freeze panes beneath row 35, but then I'm only left with about 10 scrollable rows; not going to work.

I'm game for anything if it can be done.

Thanks in advance!