Note 1 at Lk. 20:29: It is very doubtful that the situation that the Sadducees were relating ever took place. It is more probable that they were stating a hypothetical case to complicate the understanding of the resurrection and thereby discredit it.

If you accept their basic supposition (marriage continues in heaven), then their reasoning was correct. It would not be possible to administer marriage in heaven with multiple mates as their story described. Their reasoning wasn't flawed, but rather the "facts" upon which their reasoning was based were not scriptural.

The scriptures speak of two becoming "one flesh" (Gen. 2:24; Mk. 10:8) in marriage, and angels are not flesh (Ps. 104:4; Heb. 1:7,14; see note 2 at Lk. 20:36, below). Paul said, "Flesh and blood cannot inherit the kingdom of God" (1 Cor. 15:50); therefore, marriage is an earthly institution limited to flesh and blood mortals (Lk. 24:39) and will not exist in heaven.

Likewise today, many people use very logical reasonings to try to discredit God's Word but as Jesus said, they greatly err because their starting point for their arguments is not based on scripture. Only reasonings based on scripture have any merit.