There is no way to detach an original evil/sin from the effect - they are bolted together like pieces of Eiffel tower -  you pull one essential piece out of it and all is going to collapse.

A bastard child is the effect of fornication.  The cause of the child is mortal sin, but the resultant child is not a sin, nor are they to be shunned, nor is it their fault.  The act of conception was sinful; the material, bodily components of the act are not.  Those cells grew into a human being, which is not tainted (spiritually) by the original act of fornication.

Again, we hit the wall with a definition of term "copy". How do you know they are not the same? Can you tell apart an original from a copied cell? Does not entire process rely on the fact that those "copied" cells resemble an original?

I say they are copied because the scientists say they are copied.  Yes, the process relies on a copy because the original fetal cells would die and can't stay alive long enough to finish the process.
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Would the copied cell ever exist without an original coming from aborted baby? Can you recreate the process without procuring an abortion?

No and maybe not.  The 2nd point is unknown.  Can scientists use placental fetal cells instead of abortive cells?  Probably, but it's more expensive, so they haven't researched enough or it's only rare.  Practically speaking, the answer is "No, the process only works with abortive cells."
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What if a vaccine factory blow up? Do not they need a new abortion to restart everything? Once they do, could you tell apart a new and old vaccines?

They might be able to use cells from another factory, but this is irrelevant.
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Your whole point is that vaccines rely on abortion.  No disagreement from me.  But when we break down the actions involved, here is how I see it (based on my limited knowledge):
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1.  The purpose of a vaccine is not abortion.  One of abortion's purposes might be to sell fetal cells used in vaccines, but that doesn't affect the morality of vaccines.
2.  A cell is a cell.  It's an indifferent object, morally speaking.  If the cell comes from abortion, then the one who provided the cell sins, but the cell is not sinful; it's just a cell.
3.  Using a cell in a vaccine process, or copying a fetal cell is a separate moral evil from the origin of the cell itself.  Much like the analogy of fornication and the resultant child.
4.  The vaccine process is not intrinsically evil, even though the use/copying of fetal cells may be evil; it's a different evil than murder.

That child's existence is NOT a result of a sin. The fetal cell line is directly a result of an abortion.

??
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1.  Fornication --> parental cells from fornication --> birth of a child
2.  Abortion of a child --> fetal cells from abortion --> vaccine
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In #1, the original act is a sin but the result (child) is not.  Same cells involved in the sin of the parents, were not sinful in the result.
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In #2, the original act is a sin but the result (vaccine) is (arguably) not.  Same cells involved in the sin of abortion, but are not sinful (arguably) in the result (vaccine).
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It's a pretty good analogy, I think.

You are participating, but it's still a separate sin.  The original act of theft is sin #1.  Selling stolen goods is sin #2.  Buying stolen goods is sin #3.  They are connected but still separate, because a thief could steal but not sell the goods, and instead return them.  Then only 1 sin would be committed.
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Abortion is sin #1.  Cutting up a body for science/$ is sin #2.  Selling fetus parts is sin #3.  Buying fetus parts is sin #4.  Extracting fetal cells is sin #5.  At this point, all that's left is fetal cells.  I don't see how anything beyond this is related to sin #1.  You've basically reduced the abortion evil to its lowest denominator, materially speaking, a cell.
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What happens next with those cells, to me, are sins associated with scientific excess/experimentation.
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...Getting back to the car analogy, what is happening is #1 car is stolen.  #2 car is sold.  #3 car is broken down and parts are sold.  #4 car parts are bought, and some are discarded to the junk yard.  At this point, the car no longer exists.  I don't see how the original crime continues...

When you buy a car replacement part - it does not matter if the part comes from stollen car or a junk yard (assuming they are functionally the same)
When you buy pieces of killed child body - it HAS to be from an abortion, otherwise your vaccine production line would not work. So the intent of abortion still exists.

That child's existence is NOT a result of a sin. The fetal cell line is directly a result of an abortion.

I am interested in this question as well. I find Fr Scott's 2000 argument difficult (not necessarily his conclusion but how he gets there, i.e. the "direct line of causality" argument). He wrote, "There is in fact a direct line of causality, from the abortion, to the available fetal cells to the development of the vaccine, to the immunization. Therefore, the immunization is a direct consequence of the abortion, and not just an indirect effect." It is unclear to me how a direct line of causality would make the subsequent acts formal cooperation. Perhaps I do not correctly understand how Fr Scott is using the term "direct line of causality," and I would be grateful if someone were to explain that.

ElAusente...i don't think Fr Scott ( or any traditional priest) ever says there is formal cooperation.  As far as I know only Ladislaus asserts this.

I am interested in this question as well. I find Fr Scott's 2000 argument difficult (not necessarily his conclusion but how he gets there, i.e. the "direct line of causality" argument). He wrote, "There is in fact a direct line of causality, from the abortion, to the available fetal cells to the development of the vaccine, to the immunization. Therefore, the immunization is a direct consequence of the abortion, and not just an indirect effect." It is unclear to me how a direct line of causality would make the subsequent acts formal cooperation. Perhaps I do not correctly understand how Fr Scott is using the term "direct line of causality," and I would be grateful if someone were to explain that.

Here is how the new member "Canis" understood Fr. Scott's argument:

"Further, it is irrelevant that the original fetal cells of the aborted child are or are not currently present in the cell line. Those cells were the initial cause of the cell line (in all four senses of causality); what happens subsequently is irrelevant insofar as we are talking about the causal chain as a whole. Many people here have been confusing per se vs. per accidens causality. In the case of a cell line, we have a per accidens chain, but we must remember that every per accidens chain presupposes a per se causal chain. This is how I read Fr. Scott's original article arguing that using vaccines derived in any way from aborted fetal cells is gravely immoral because there is a direct line of causality, that is, the entire chronological development of the cell line ultimately depends on the initial fetal cells. I think arguing this way is a bit ambiguous, but I think it is trying to overcome the objection that the original cells are no longer present [Not a fact anyway, however -SJ] . The ambiguity of arguing like this also shows itself in the somewhat convoluted thought experiments given earlier to show how cooperation in some evil act would be formal vs. material."

https://www.cathinfo.com/profile/?area=showposts;u=6632

I'm betting my last dollar that Canis is a Dominican priest.  He said his piece and never came back.  Nor did he tangle with anyone.

He also mentioned that the morality of this issue can only be determined by double effect analysis (an analysis Don Curzio Nitoglia proved beyond any dispute fails in 3 of 4 criteria).