Adding filesrc element to playing pipeline

[Baby Octopus]

Hi,

1. I have a pipeline which is running
2. I intend to capture SEGMENT_DONE message and then create a new branch in the pipeline which has
    filesrc ! decodebin ! video/x-raw ! ...would go to already existing input selector. Each new element, while adding to pipeline is made to sync with parent

All this happening when pipeline is in running state

I'm getting an error from basesrc that it isn't linked

What is that I should take care while doing this?
1. Should I be pausing the pipeline while doing this
2. Should I put all elements in NULL state instead of syncing with parent?

ANy help would be appreciated

Thanks,
BO