reconnected clips

I imported clips from camera into FCPX (they were prores 422)- synced the audio (was recorded separately) and then exported a low res mp4. That file was then edited in Premiere and the XML of the rough cut was exported.

I imported the Premiere XML into FCPX using SendToX and was able to relink to the exported low res clips, but now I'm stuck and need to some how replace the low res clip that was used for the rough cut - to the original files from the camera for finishing and color grade.

I'm sure I didn't do this right from the beginning and would love to know the best way to do it, but at this point I'm trying to figure out if what I've done is salvageable.

I tried "Opening" the exported low res clip in the FCPX browser and putting the original camera clip and audio within that "container", but when I go into the timeline and "open" the clip - the change I made in the browser isn't reflected and it's still just the exported low res file.

Not sure what to try next. Any help would be appreciated.

For regular clips, when you put it into the Timeline, that's basically a new copy. Select the clip in the Timeline, Shift-F to reveal it, with the used range selected, in the Browser. Do and overwrite (Replace) edit.