Dev manager participating in Backlog Refinement

Is the dev manager part of the development team or is she playing a role of the scrum team for the poduct? Only the PO and DevTeam should be participating in the refinement sessions of the sprint.

You as the scrum master must assess whether external interactions with the scrum team are helpful or not and act accordingly. Have you asked the dev team how they feel about this? Do they/you see value on the way this manager is 'helping' or, on the other hand, is it an impediment endangering the correct development of the self organization of the development team?

He is not part of the development team. He manages each of the members of the development team.

I haven't asked the dev team how they feel about it. They are almost all quite junior as it is a new team, my sense is they would not see the harm this could cause. I see some value in his knowledge and experience in the meetings, however I do feel it will endanger the self organisation of the team. Any advice?

Have a chat about team self-organization with him, ask if he sees any problems with the current set-up, and then explore what he thinks might be done about it.

Is he new to scrum? I have seen this behaviour when the traditional managers are newly introduced to scrum, where they still hold on to the traditional methods.

Have a one to one talk with him, to make sure he understands the agile model and see how you can leverage his knowledge to the greater good of the team and project.

If he is insecure, try to get his buy-in by explaining the process and obtaining his confidence, and as Ian said, get his opinion on the current set-up.

Sometimes, it is very hard to relinquish the control.

--Anoop  

Just my opinion, but the Dev Manager seems to be holding on to past behavior that he may be comfortable with, but actually harms self-organization within the team.   Scrum and Agile are about fundamental changes, and not re-labeling existing practices to fit into Scrum.

Why does the Dev Manager feel that the "work" needs to be processed by him before it is consumable by the team?   Why does he have any action items from a refinement session?   Ultimately, the main question is why doesn't the Dev Manager trust the team?

I also think that some flow of communication must occur. 

As identified by @Anoop and @Timothy some reasons for this behavior could be traditional management background, lack of knowledge on agile models or lack of confidence/trust on the team (junior team?). Perhaps he is doing it out of own initiative thinking he is doing right when for real he is endangering the self-organization of the team, or he is simply asked to do that by someone up the hierarchy so the problem might come from another different spot. 

I'm just guessing possibilities and probably the real one is not amongst them. 

@Kaizen: It'll be nice to know the real "why" to this issue if you come to figure it out at some point. Please post back! :)