Hi Mary Jo,
I have been told all my life that the spellings you indicate are part of our history, the evolution, of my Blocker family spellings.
It is also rumored in my family that Field Marshal Prince Von Blucher (with an umlaut) is an ancestor, although no proof exists to verify this possibility. Field Marshal Von Blucher lived from 1742 to 1819. I believe the first Blockers from whom I am descended arrived in the colonies in about 1740, so the most I could hope for with regard to the Field Marshal is that he is a cousin to my ancestors. I do like thinking, though, that somehow the same stuff of which Field Marshal Prince Von Blucher used to defeat Napoleon at Waterloo is that stuff of which I am made.