i can’t ATM.
its simple, when you known how work and understand some concepts of engine/blueprint. 3 day ago i in the same boat… lost 
1.- Create a Blueprint “Itempickable”, you going to use that BP for all your items pickable, changing the mesh, if you need attributes for each items create vars a make that vars public
2.- Create a blueprint “backpack” with “Get Backpack” “Drop Backpack” functions and array “BackPack Inventory”, that array MUST NOT BE object actor/object, must be “Itempickable”,
3.- In character create a var “Backpack” type object Backpack, a socket in back of your character (HeroTPP)
4.- Use single trace in your character example by pressing E, and use “Hit Actor” for save(set) this in the backpack var in character for reference when you need, continue that “Break Hit” line, if the “Hit Actor” “isValid” , cast to backpack, if cast not fail the item its BP backpack, then you can call “Hit Actor->Take backpack” or if you set your variable “backpack->Take Backpack”
5.- In Take Backpack, do the attach to socket(snap target, rotate if its necesary) , disable physics and collisión and that stuff
Remember compile, if you don’t see any of this variables or functions.
The trick its use that especific object, not a actor/object or other, if you use a specific object you can call and communicate with the others BP easy, because engine known its “Itempickables” or “Backpack” and her functions. You can anyway “Cast to” specific type and if cast not fail … …
Try play with this