Thanks for the suggestion. I have used Rootsweb.com and a few others successfully over the years to find my relatives in Canada and Scandinavia, but was not aware country-specific adoption boards existed on ancestry.com. Thanks for the tip.
I know my search is like looking for a needle in a haystack, but that my father had a Czech mistress during the war is certain; that he wanted to stay with her and leave my mother is also certain; that the mistress was pregnant is a very real possibility, so I will search for as long as I can to see if this was the case. Thanks again.