Pilgrim, you asked for Scriptural evidence that all infants dying in infancy are elect. I don’t think there is one passage that clearly states such. I have already mentioned some relevant passages, but here’s another:

Millard Erickson, 2002 president of the Evangelical Theological Society, gave an example of an infant who died but would be seen again in heaven: “David had confidence that he would again see his child who had died (2 Sam. 12:23).”

(Millard Erickson, Christian Theology, page 654)

Robert Bergen, Associate Professor of Old Testament at Hannibal-LaGrange College in Hannibal, Missouri, agreed with Erickson’s interpretation: “Though David was now bereft of his son, the separation would be only temporary. There is to be heard a note of consolation in David’s words ‘I will go to him.’”

(Robert D. Bergen, “1, 2 Samuel,” The New American Commentary, ed. E. Ray Clendenen, vol 7, page 376)

The famous radio preacher J. Vernon McGee also commented on this passage:

“David knew that the little baby was saved. He said, ‘I will go to him someday.’
David knew that when death came to him, he would be reunited with his son.
A child dying in infancy goes to be with the Lord. Matthew 18:10 says, ‘Take
heed that ye depise not one of these little ones; for I say unto you, That in heaven
their angels do always behold the face of my Father which is in heaven.’ The word
angels in this verse should be translated ‘spirits.’ When a little baby dies today,
that baby goes immediately to be with the Lord. That is the teaching of the Word
of God.”

(J. Vernon McGee, “1 & 2 Samuel,” Thru the Bible Commentary Series, vol. 12, page 243)

You said, “And "Blood Illustration #3 (Modified Calvinistic) is a misnomer... it has little in common with Calvinism at all. It's semi-Pelagianism, if anything. That view denies the very definition of the deity of God; Omnipotence, Omniscience, and Omnipresence.”

I don’t see how it denies God’s omnipotence, omniscience, and omnipresence. God knows everything about everything, including non-actual, imagined circumstances. God has always known that non-elect people would refuse to surrender to Him in repentance and faith under any circumstances in any imagined world. The Westminster confession says that His knowledge is infinite. It also says the following: “Although God knows whatsoever may or can come to pass upon all supposed conditions; yet has He not decreed anything because He foresaw it as future, or as that which would come to pass upon such conditions.” I agree with this statement. Notice that it mentions all “supposed” conditions.