Like the tittle states i Have added box Compoent on my new Mesh and have made a new storage box child with the Mesh, But sightly lost into how t get it when the Actor Overlaps item is added to the new storage box?
Currently it is not possible to add/remove items to/from (structure) inventories in Blueprints. However, they promised us “unlimited power” with the next update of the dev kit. I really hope that this feature will be included. Update should arrive any moment now, as well fingers crossed.
Dang it cant do anything untill this new update, All well.
I do not mean to be a “downer”, but the new update will allow you to read/write any variable through blueprinting. It is entirely possible that the inventory component of your storage box will be considered a variable that is read/writeable, but I wouldn’t want you expecting something that isn’t guaranteed. I’m not saying it won’t be possible, but it might not be. Better to just say to yourself, we will see when it comes 
Dam Azrael getting me more excitied to see the powers of this new update, The Devs have done such a wonderfull job at hiding from us :).