Can we add blueprint script to mesh Actor without affect to any actor reference?

Hi,

I am new to UE. I am working in the project that there is Mesh Actor in the level. This mesh actor is used by another actor in the level. And I found later that, I would like to add blueprint for the behavior of this Mesh actor.

I press a button to add blueprint script in the Unreal Editor, but it is found that the mesh actor is disappeared and blueprint containing this mesh appears instead. Also, I have to rearrange this new blueprint in the world. When I run it, UE crashes. I have to roll back.

Is there a way to attached bluescripts to the implemented Mesh Actor and it does not harm the existing implementation?

Thanks a lot of any advice in advance.