Choshen Mishpat: Giving work to daughter

This question came to the Beis Horah last week:

Someone who is magia seforim takes (lets say for example) 100 shekels to do a cerain job. He however decided to get the job to his daughter to do instead (who does just as good a job of him) however without the knowledge of the one who gave over the sefer. He pays his daughter 80 shekels and keeps the other 20 shekels for himself. Is there any shailo in this? If this is a problem to where can one find a source in Shulchan Aruch or Poskim?

Choshen Mishpat: Parents not paying Rent

The following shailo came to the Beis Horah recently.
One set of parents of a young couple rented an apartment for them. They signed on the contract for the apartment and agreed to pay the rent every month -- however it would be the young couple living there. After a number of months the Parents stopped paying the rent. Can the landlord be tove'ah the young couple in order to get the money? Or does it only go on the parents since they signed the contract and agreed to be the ones to pay the money. It was paskened that the landlord can be tove'ah the couple. However I still would like to be m'ayin into this more and find a clear re'ah (one way or the other.) If anyone has any thoughts, please comment!