Do you get snapshots or baselines in the pending changes view? If you create a snapshot RTC usually automatically creates baselines with the same name as your snapshot. And baselines follow the flow between streams and repository workspaces. Thus you will see them as incoming or outgoing events.

I would suggest to look into the library and read about RTC SCM. Start here: https://jazz.net/library/article/126 there are a host of documents as well: https://jazz.net/library/#sort=pubDate&tag=scm

Baselines are basically configurations of element versions of a component that belong together. They flow like changes. You deliver them after you create them on a repository workspace and you accept them if someone created and delivered them to a stream.

You can flow from one stream to another if, and only if, there are no conflicts. The main usage is to promote a new state f a stream to another (e.g. from TEST to PROD). Typically there is only one direction of flow and thus conflicts can not happen.

If you have conflicts, you have to resolve them using a repository workspace.
The typical flow is to have a workspace W1 based on Stream1. They are in sync. Then you change the flow target to Stream2. You get differences between W1 and Stream2. You accept changes from Stream2 into W1 and merge conflicts if needed. Once done, you can deliver the changes to Stream2. You change the flow target back to Stream1 and can deliver the merged changes back to that. At this point the streams are in sync.