no one will be any the wiser

(and) no one will be (any) the wiser;
and no one (is / being) the wiser;
nobody (is / being) the wiser;
without anyone being the wiser

1.
(= No one will ever know; No one will ever notice something bad that someone has done — ~ и никто ничего не узнает; ~ никто и не догадается; ≅ (и) концы в воду; ≅ (и) все (будет) шито-крыто

So, for example, if you were to commit a murder and then your friend gave you an alibi, no one would be the wiser — i.e. no one would find out, no one will ever know — so go ahead and get away with as much as you can.... But be warned, someone else always knows!

Example 1: We can pour some of dad's gin out of the bottle and replace it with water, and no one will be the wiser.

Example 2: Take the label off the jar and say you made it yourself. No one will be any the wiser. (CID)