Signing a rental contract

Hello everyone!

We found an apartment, but there is an issue we cannot figure out before signing the contract.

The real estate agent sent us the contract for signing and there is the name of the landlord stated. We checked out the information about the property in Kadaster (https://www.kadaster.nl/), and found out that the owner of the property is a different person. The landlord and the owner have the same last name but the first names are different. The agent told us that they are relatives and that an uncle of the owner manages the property on his behalf. He also said that this is a common situation here in The Netherlands that families have these property businesses together and that a verbal agreement between the relatives is enough to make it official.

So the question is that: is it true that we don't need to worry or there should be some kind of document proving that the person has the right to sign a rental contract on behalf of the owner? Just in case something goes wrong will this contract be legal or not?