Linking up multiple spreadsheets

Hey guys!

I am in a bit of a situation and I don't even know how to search for it (I really tried). I need to link multiple spreadsheets and gather data from them.

Here's the breakdown of the situation:

Main spreadsheet - Contains all customer data, such as name, address, phone number, email, notes, etc.. You get the point.

For each individual customer I will be having a Profit and Loss spreadsheet, which contains more and specific information, but also the information that will be found in the main spreadsheet. Every customer will have a folder which also has the P&L spreadsheet in it.

Is there any way I can make this more streamlined, besides double inputting all the data in both spreadsheet?

I want the main spreadsheet to pull up the information automatically the data from each individual customer. I create the P&L where I will be filling out the information then I want the main spreadsheet to automatically get the data from that, as simple as possible.

Sorry if this is a little confusing, I am trying my best to explain it haha.

Thank you!