Linking Audio and Video

Ok, so I'm editing a feature where the video was recorded and captured separately from the audio. I've gone through and synced up each "take" to the audio for that "take" in sequences. No problems there. However, because I'm editing 1080p ProRes in a 720p ProRes sequence for the final film (want to be able to re-frame, pan, and zoom), whenever I drop a "take" sequence within that main sequence it must render before it will play at all. If I drop just a video clip (not synced with audio in a nested sequence) it will play just fine (albeit preview quality). How do I overcome this? I know I could export each nested sequence as it's own Quicktime movie with the audio included and use those. But that is doubling my harddrive space and taking lots of time. I need to just link the video with the synced audio so I can drag them as a single clip into the primary sequence OR figure out a way for FCP not to have to render just because it's a nested sequence. I appreciate any ideas!