Having scanned a text or two, I'm still not sure that Bassanio helped the lovers perform their escapade, though it is implied that he did. More certain is that he has "disabled" his "estate." He asks Antonio to help him obtain another loan. Shylock agrees to supply the loan and sometime after agrees to join them for supper. While Shylock is away at supper, Jessica and Lorenzo elope. Bassanio also hires the clown as an employee.
Bassanio, before heading for asking Lady Portia's hand in marriage,helped the escapade of the lovers Jessica (Shylock's daughter) and Lorentzo (one of previous soldiers of Shylock). He helped them to escape from Shylock and Venice by sailing them in one of Antonio's ship. After arriving in Belmont, he heads for wooing Lady Portia which he is able to do successfully by choosing the right casket. He chose the Lead Casket containig Lady Portia's portrait and thus, won her hand for marriage.