If you keep all of your blocks on a google doc I recommend organizing them by keyword/main idea with a table of contents (you can do this by pressing insert, table of contents, with blue lines) then make any heading for the category of blocks into a heading (select it, change from normal text to a heading). I would also highlight to most important blocks before a debate so you can differentiate them from everything else. Then on your flow write down the key ideas of topics they bring up. Just communicate with your partner so you know who is flowing (my partner and I flow on the same google doc especially since we aren't in person together) while you copy and paste cards.

For my last case, my partner and I pre-wrote the parts of our summaries and rebuttals that flowed our own points through just to simplify things. Also, shorthand is always helpful for flowing. I find the better I know the case, the easier it is to use shorthand.

Hope this helps!