Need help in understanding XPUB derivation paths

Hello guys! I really tried everything to understanding alone, but i've something i really can't figure out.

I discovered my bitcoin XPUB through Ledger App. I need to give him to my accountant (who i definitely trust) for documentation purposes. Problem is, when opening the XPUB, it shows each pool of transactions made from that XPUB, and not just my transactions alone. So, it is impossibile to understand which transactions are really mine. I can't say i own that XPUB, because someone may say that 80BTC transactions are mine, which are not. Extracting ZPUB from XPUB actually shows only my addresses, but on ledger only the XPUB is shown. How can i explain that, in that XPUB, only some transactions are mine? And be totally safe with the law? It would be a disaster if someone told me i moved an amount that wasn't really mine, just for an address mistake!

I know derivation path can help somehow, but it didn't get something. XPUB is a key generator not owned by just one user, but from many users, and we can distinguish our transactions in that pool because we all have a different derivation path (so, one XPUB, multiple derivation paths), which confirms which transactions are really ours. Am i correct?

I have many confused thoughts as you can see.

(Edit: I have lost my passphrase but have access to the account, otherwise it would be simpler to demonstrate it)