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I looked at Thankfulʻs profile. There is a link to her birth/baptism that shows Cyrus Nickerson as her father.
The profile for Thankful is well sourced. You should look at some of the other links to satisfy yourself that Cyrus is the correct father.
If that is the case, you can add Cyrus as her father, with sources that confirm the relationship. You should be able to add her mother, too.
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