Bava Batra 144: Acquisition of a House, Shushvinus

The rabbis discuss how to understand a son's acquisition of a house.  Does a son automatically acquire his father's home?  Well, if the father does not live there, and if this is the oldest son, and if he marries a virgin, and if this is his first marriage, and if he is the first son to be married?  Perhaps he only acquires a part of the house?  Must the house be completely unused? What if a dovecote was in the house - and the house was actually a storehouse?  

Believing that having any item of their own in the house would prevent their sons from acquiring their houses, rabbis left just one sandal or just one cup of oil in the house.  Some rabbis believe that if a man leaves all of his possessions to his wife, he is not preventing his sons from inheriting.  Instead he is ensuring that his sons honour their mother.  

We learn a new Mishna which teaches that if brothers inherit together and one of them then gets a well-paid job, the brothers share his income.  If one brother becomes ill, the other pays for his treatment.  

The Gemara considers the circumstances that might have been behind this Mishna.  For example, was one son conscripted to the king's service?  Was one son named a tax collector?  Must the sons recognize that one's success is due to the other?  The rabbis discuss a baraita that teaches if one brother takes money from the estate to learn Torah or a trade, the other can say that you must live here to continue to receive food from the estate.   Rav Huna explains that a house is more blessed when more people are there.  Rabbi Chananel suggests that it is more economical to live together, for example all people can benefit from just one lamp.  

When discussing the cost of illnesses, we learn that some rabbis believe that all illness is from heaven except for fevers and colds, which are due to our poor self-care.  

We learn a new Mishna regarding shushvinus, the custom of bringing gifts to a groom knowing that the gift-giving will be reciprocated in the future.  If the father sent shushvinus with some of the sons and then the groom returned the shushvinus after the father died, do all sons share them?  We know that shushvinus can be collected in a court, just like a debt.  If a man sent wine and oil to another man who is not a groom, the court does not force a reciprocal gift, for this was an act of chesed and not of obligation.

The Gemara considers who should keep the shushvinus that is given just to one son, or to sons after the father (who gave the original shushvinus) has died.  If the shushvinus must be returned, how would that happen?  Is shushvinus something that one person can do to another?  The return of shushvinus is discussed at some length. Who would pay for these unused gifts?  What if they were returned to heirs?  Is is necessary to create a painful circumstance?

It seems that there must be much more to know about shushvinus.  The halacha regarding this practice seem to be based on custom rather than Torah law.