Hello Ghawauzimb97
Good day.
I second my friend’s @Tafunge25 ’s advice.
However, for a better advice, it would be good to know the traveller’s age.
In my opinion, one of the most cost saving ticket combination would be the Berner Oberland Pass plus the Swiss Half Fare Card. The latter offers free travel to children up to 15,99 years of age thanks to the complimentary Swiss Family Card. And, if you stay in a hotel or a legal AirBnB in Lucerne, the city transportation is covered by their Tourist Card.
Kind regards,
Roland