...with the motivation(s) behind the question (I was at one time, a studious PK). ;) This account of the myth is part of a series of other attempts wherein the Sanhedrin Council seeded agents and provocateurs among his followers in an attempt to trap him into making statements that would give them the justification for ending his ministry. One way or the other.
He had scorned them publicly for their false piety. Their loud ostentatious praying, their adulteration of the Temple by allowing money-changers to do business there. And contrary to the other Rabbis, he spoke mostly about the aspects from their beliefs that were in-keeping with OT tales and stories which dealt with issues of human kindness, forgiveness and humility, rather than righteous retribution and strict adherence to law. He was the
Populist with a new and invigorating message, to their
dull Establishment droning about laws and rules that they themselves failed to adhere to.
The parable's subject matter illustrates not only how the law worked (7 dead brothers, 1 infertile wife(?) and how this method supported the retention of the dowry from that initial marriage - and not noted is the fact that in all likelihood she was a cousin to all those husbands), but also it reinforces the fact that they believed that children (preferably sons) was the means by which one achieved immortality -- through their progeny. As the verse above states, "
the Sadducees, which say there is no resurrection," reflects the underlying belief then held by the Hebrews. So in advancing the idea(s) about a hereafter, he was both "adding to" the narrative as well as "undermining" the existing one, along with long-held beliefs and interpretations as had been advanced by the Rabbis that preceded him.
The basic problem for the Sanhedrin was that they could not refute what he preached because the issues he spoke to did not conflict directly with "The Law." Only a differing interpretation of it. What he advanced was "new stuff" that they had no ready-made answers for. What he preached was supportable within their overall beliefs of the time (which included more than just the beliefs found in the Torah). They could only disagree with his interpretations -- which is something that was routinely done between the Pharisees and Sadducees themselves. And it is also why they needed to "catch" him making a mistake. A mistake like claiming to be the son of their god - a blasphemy, punishable by death.
The questioner, in raising the point of "the resurrection" was using Jesus' own language and concept in an attempt to trap him. Not having any background or understanding of such a thing as a life after death, they used the existing social structure that passed wives down the line from their deceased brothers as a ploy to undermine the whole concept of the resurrection. They assume that the "life-in-the-hereafter" that Jesus spoke of, would be more or less similar to the one that they knew. Why else would they be asking questions pertaining to the "disposition of property" (the wife), in the hereafter? Apparently, the idea that she would not belong to any of them, never entered into their thinking. Because such an idea on its face, would be foolish at the time.