Hi, I´m new here and not so good in English, but I’ve give it a try and hope you understand.
The whole idea of the overlapped generation is not only illogical, there are also serious errors in reasoning and how to interpret the scripture.
The only "scriptural argument" that the Governing Body has managed to bring in this matter is Exodus 1: 6 where they say that a "generation" can be stretched to cover a longer period than usually meant by a "generation". But, as said, here are serious problems.
When David Splane interprets this scripture he says that "that generation" is the same period as Joseph's lifetime, and all people during this time shall be compared with Joseph's lifetime. Splane states that if someone lived, if only for 10 minutes, at the same time as Joseph, he belongs to "Joseph's generation," and this is the great error made because the scripture does not speak of "Joseph's generation," as if it was his.
It is said: "Eventually Joseph died, and overpriced all his brothers and all that generation." What was included in "that generation"? Shortly before, in verse 5, it states: "And all of Those Who were born to Jacob were 70 people. [...]" So the "generation" spoken of in verse 6 is not only about Joseph, but also his 11 brothers, and 58 other people, the whole Jacob's descendants, in all 70 persons. So you cannot do the thought experiment that David Splane and the Governing Body are doing here and talk about "Joseph's generation", one cannot "steal" the generation from Jacob and make it Josephs, and only have him as reference. The generation started with Jacob and included at least 70 persons who mostly lived during the same time and experienced the same things, not just one person who you can compare whoever you want with and anytime.
Siblings can be said to belong to a "generation" because they have the same father, One can then say that the father started a generation, and when siblings die out, that generation also dies. That is what clearly mentioned in these verses as I see it.
And the most
important: there is no "overlapping" mention or hinted here.