"Quotations" around Syaoran's or Sakura's name will refer to the Syaoran or Sakura present at the end of the TRC manga (aka both Tsubasas)
When Syaoran and Sakura "died", they were reborn in Watanuki's timeline. Once together again, they gave birth to the original "Syaoran", Tsubasa. (the basis for the clone). It is assumed that due to the nature of this paradox, that the clones of Sakura and Syaoran were reincarnated as the originals in Yuko's timeline, meaning that even though they are just clones, they have been reborn as the real thing. This is not debatable, as the clones now have the correct set of parents and grandparents (identical to those in the Cardcaptors world). Because Tsubasa-"Syaoran" has Syaoran and Sakura for parents, he cannot be the original in that timeline, but morever, just a second Syaoran, created by the paradox.
Next, via Yuko, Tsubasa-"Syaoran" heads to Clow Country to find the original Tsubasa-"Sakura" of Clow. Events transpire, leading to Watanuki's creation, because his existance is needed to take the place of Tsubasa-"Syaoran" in Yuko's timeline. But therelies a wholst of problems.
-If Clone Syaoran was reincarnated as the original in Yuko's timeline, why was there a need for Watanuki to replace Tsubasa-"Syaoran", who does not exist in any other timeline??? Is it just becaus ehe is a bi-product of the paradox?
-If Tsubasa-"Syaoran" travels to the world of Clow, where Tsubasa-"Sakura" exists, wouldn't there already be a Syaoran that was naturally born into that world? In other words, doesn't Clow Counry have ANOTHER Syaoran somewhere?????
-(this one is probably unanswerable) What would happen if other Syaoran and Sakura's from other worlds had children; worlds unaffected by the paradox??? Would they give birth to Watanuki??? Tsubasa-"Syaoran"? Or their own child not seen in Cardcaptors, Holic or TRC???
-What is the meaning behind both Tsubasa's sharing the same name?