If these are profiles that you added, then they should already be on your Watchlist. If you're talking about someone else's tree, created by another WikiTreer, then the only way to get those profiles on your Watchlist is if the Profile Manager of those profiles adds you to the Trusted List for each profile. This can be done in bulk. But you can't add yourself to the Trusted List of someone else's profiles.
I hope that answers your question.