How to add value from one file to ONLY ONE CELL in another file?

[saziz]

Hi all, 

I need to add one value from a file to ONLY ONE CELL in another file. I managed to do that with a number of tools but it made the workflow super long. Is there a specific tool that can do this? Currently this is how my workflow looks:-

I need to add the value above (under summarized tool) to one row (row with GL Code 100500) in another file, see below:- 

The value under summarised tool is actually the sum of the whole 'Grand total' column in the first file, and this sum should be added to the specific GL code in another file. I had to filter out the GL Code from the second file and add formula tool to assign GL code for the sum from the first file before I could add them up. Is there a more simplified way of doing this? Perhaps a tool with this kind of function? 

[Qiu]

@saziz 
I think your approach is already good. 
Since we only have information about the Account code, so Joint, Find Replace and such will not work...