A. I might be way off here, I am just giving you my opinion on it.
B. Lets look at a different way:
I have a goblin grunt with bear strength and an orc butcher with a hidden bear strength, lion savagery, and a hidden enchantment transfusion.
When I activate the transfusion and attempt to move the enchantments from the butcher to the grunt, can I knowingly move the hidden bear strength to the grunt? No.
Why? The grunt is not a legal target as per the requirement of E-tank.
Pg. 18 Rule book V 2.0
"
There is no limit to the number of different enchantments that can be on an object, but each object or zone cannot have more than one enchantment with the same name attached to it at one time. This includes both hidden and revealed."
The E-tank never moves the bear strength from the orc to the goblin in the example above, but can move the lion savagery.
Same thing happens to the gorilla: the target must be a legal target of the eagle wings, which it is not because it already has an enchantment named eagle wings attached to it.
I believe legal relates to the target line:
"living creature"
"non-mage creature"
"mage"
"corporal creature"
etc etc.
If that were the case then you could E-tank/shift enchantment a plagued to an iron golem, which you can not. Because