Transaction Wallet-Address extraction

When taking a look at the blk.dat files I am confused about how I would go about getting sender(s) and receiver(s). It is clear to me that if I have multiple inputs / outputs that there might be multiple senders / receivers but how do I determine them?

If the transactions in the blk files don’t allow for that then how do I figure out who sent who what?

I do not need a 1 to 1 mapping of transactions, if 5 people combined sent 7 other 3 BTC that is perfectly fine for my purposes as well.