Win10/Office 365/Excel 2016

I may be asking the question incorrectly so I'll explain--

I just downloaded 3 separate brokerage accounts from the same brokerage company (thus, the formatting of each book is the same). They are .csv files.

There are a number of equities that repeat (owned in) in more than one of the accounts (e.g. Apple shares are in workbook A, B and C). My object is to consolidate the 3 accounts/workbooks into one. After which, (and this is more a wish list sort of thing) add any instances of the same company that's listed more than once together as one listing for the total. The new solitary spreadsheet does not need to attribute ownership of any of the stocks to the various accounts. I just want a sheet that lists each company and the corresponding total # of shares. I then import the total csv file to my iOS Morningstar app.

I currently do this manually: copy workbook A to new workbook D, copy B to D, copy C to D then delete the repeated instances of a stock keeping one listing of the stock with the running total of shares.

Questions:
1. Is there a way to 'automatically' merge the 3 books (A, B, C) to the new D?

2. Is there a way for Excel to 'automatically' combine multiple instances of a particular stock found in the integrated D workbook into 1 stock and delete the other instances after the stock consolidation/addition?

Mark