I can certainly see that you believe your questions have substance........
........I can also see that some of your posts, on this subject, are becoming "off the wall" in desperate attempts to find something which points to JB's innocence. What you offer is pure conjecture, ie, it could be X, it could be Y, it might even be Z, leaving me uncertain about whether you really care, OR whether it's another opportunity to have a dig at "Establishment"
No Jane, it's pretty simple.
If you believe the dark spots are the end of the process, then you must believe that the underside of Sheila's wrist is the begining of the process. Therefore - you have to work out
how and
when the blood was transferred to the underside of the wrist.
If you believe that Sheila was killed by two shots in quick succession, then you have to factor-in that limited time frame and circs, when working out how the blood transferred to the underside of her wrist.
If however you believe that bloodstains don't of themselves puncture skin, and the dark spots are the
source of the blood trails, then you must believe that underside of her wrist is the
end of the process.
When factoring in that June is one of two possible assailants who could have caused such wounds, you have to take in to account that June herself received gunshot wounds. Then you have to consider whether or not June was capable of putting up a fight after having received any of her shots.
The only weapons June had were her own fingernails.