That is in order to be adopted into the noble household of the bride which has only daughters or to cleverly enter a noble household, that has no children, as adopted child.
At this point, the probability of that happening is so low that it is close to being a miracle.
Continuing, it is also possible to marry into the retainer household of an important noble.
Usually even that is difficult because one has to be agreed upon by the fellow retainers or be accepted below the second son of the lord.