"Fanwank" is, however, a good way to describe the idea that all Founders are the same individual and that there are no innocent civilian Founders...
"The ocean becomes a drop. The drop becomes the ocean."
Isn't that pretty much the way the Female Founder described her/its/their relationship with the Great Link? Do you really
suppose the Founders have the exact
same concept of individuality as Solids do?
And the infant Changelings that were sent out wouldn't be part of the Link, wouldn't be on the Founder's planet, and wouldn't be in any danger from the disease Section 31 infected them with, or bombardment by an armada such as by the Cardassio-Romulan task force.
If there are "child" Founders, they're apparently created on an as-needed basis; there's no evidence that child Founders were in any danger during the war because there's no evidence that they existed
And Odo was infected in 2372, not 2371. The war itself started at the end of 2373.
Sure, infected in 2372, but what was the lead time on developing the virus? Surely it didn't spring into being the minute it was wanted. Clearly someone in the Section 31 leadership, if such a thing exists, saw a potential threat years ahead of anyone else in the UFP, and had a weapon prepared in the meantime. Sure enough, the situation degenerated, and the weapon was deployed.