Another thought on the newphew scenario would be.....
Thomas Windsor had a sister who married Edward Howse. A deed from Edward Howse to James Brown, dated 1800, shows Edward to have had a wife named Anna (Montgomery Co. Maryland deed book 0, p. 381.
Again, Catherine Windsor may have had a sister, Anna, who married Edward Howse. This would still make Catherine's children nephews and nieces of Edward Howse.
I am glad Jim Brown put out this new infomation as it opens up the possibility of an extension to the family of Thomas or Catherine Windsor, after all one must presume that that they had brothers and sisters and were not the only child of their parents.
I am inclined to believe that Catherine's maiden name was Baden since her grandchildren have stated so and since the name Baden continued down in the family.
Therefore I think what we may have is a long lost sister of Thomas or Catherine who married Edward Howse.
This means that the sister of Thomas Windsor could have been Anna Windsor who married Edward Howse.... or Anna Howse could have been a sister of Catherine Windsor.
The point is, why assume that Edward Howse is the brother of Catherine Windsor, rather than the brother-in-law.