Bill is probably considered a stop word and hence always rejected.
You can turn off the stop word feature (Option -> Remove Common Words -
> No).
If you don't want to do that, manually change all reference to Bill to
Bill~
The word "Bill~" will be treated as a word, and since it is not a
stopword it won't be removed. During placement of this word, "Bill~"
behaves just like "Bill".
-- Hardy