Go to the location below and add a new Actor input to the function and call it Actor. Then connect to up like shown in the image below. Then compile and save.
You will now need to go to the BP_PlayerBuildingComponent and compile it then save then do the same for the BP_MasterBuildPart.
Next go to the DestroySupportingBuildParts function in the BP_MasterBuildPart and create a new local variable, you can do this in the My Blueprint panel. Set the new variable to Actor type and call it OverlapActorL. Then create a second variable with Actor Type and set it to an Array and call it Check ActorsL. If you dont know how to make a variable an array copy the video below.
Next create a new variable called FurnitureCheckSize and set it to a Vector variable type. Then set its X Y Y values to 300 and tick Instance Editable.
Next copy the images below by adding the highlighted nodes.