FCP Timeline

Nice video my bro but i have a problem i have to sync 2 cameras and they have 2 audios each one so far so good i selected the videos i click sychronized clips and fcp created a new sycronized clip
then i selected and i press open to timeline i am done with the montage until now all good but i want to continue with my work but my timeline isn't the same, i was finished with my sychronized clip but i have more clips to add, my timeline is black-grey and it have blacks sidelines i thought that issue maybe happening because i have my syncronized clip open to my timeline i try to close fcp and re-open it....i am done with the color and blacks sidelines but my sycronized clip is not looking good when i scemed or leave to play it but when i open it to my timeline is all ok.....do i have to worried i should leave it to render ? can i do manuall rendering? when i go to export it will be fine? (i am using fcp not x)

After you've synced the clips you don't need to open them into the timeline. You make a new project and edit the pieces you want into the project. You don't edit into the clip.

Thank very much Tom for your usefull advice, i really appreciate that!