User fbrereto asks about how to use Ancestry.com to share a conclusion that is based not on proof, but on "some accounts." I interpret "some accounts" to mean there exist some sources (including some family tradition) that reports about this sixth child, but that proof is lacking.
Fundamentals
See Elizabeth Shown Mills, Evidence Explained ..., 2007 (p. 17) for "Conclusion: Hypothesis, Theory & Proof," in which she explains how conclusions can be categorized as one of three types, "each of which carries a different weight." Her categorization types follow; I have added my own summary as to the meaning of each.
- Hypothesis: Something is "possible" (might be true) but has yet to be tested.
- Theory: Something is "tentative." The hypothesis has advance, looks promising, but may remain to be tested against other theories in the real world of a "reasonably exhaustive search" and accompanying written proof.
- Proof: The home run. Genealogically/historically speaking, you are able to convey and document your notions together with all of your logic and reasoning in a written genealogical proof.
During the research process, you may frequently ask yourself, "is this him/her?" You are probably forming a hypothesis. After extensive research, you may still be uncertain. You have a theory that is as yet unproven ...
If you use a genealogical database or online web service, you have the option of sharing your "research-in-process," or only sharing that which you have proven.
If you share your work-in-process, then you probably face the question fbrereto is asking. In his case, he has an old genealogy into which the author narrated about notions about a relation that fell short of "proof."
Ancestry.com trees
To my knowledge, Ancestry.com is like many database systems, it provides the ability to add a related individual (spouse, parent, child), but there are not obvious mechanisms to communicate whether that conclusion is based on a hypothesis, theory or proof.
(a) While many of us would like more overt solutions, a proof (and/or proof-in-process) can be communicated by a comment to the individual's Ancestry.com profile.
(b) Notions that fall short of proof ("hypothesis" or "theory") can be communicated in the related event "description" field (for parent/child, this would be a birth event; for spouse, this would be the marriage event).
These are only suggestions; I doubt either of these work arounds are widely used or recognized.
Update/Edit
I would not want my words to undermine the importance of the distinctions between genealogical hypothesis, theory and proof.
From About.com, Kendra Cherry, "Introduction to Research Materials: [part 2] Theory and Hypothesis"
[T]he difference between a theory and a hypothesis is important when
studying experimental design ...
- A theory predicts events in general terms, while a hypothesis makes a specific prediction about a specified set of circumstances.
- A theory has been extensively tested and is generally accepted, while a hypothesis is a speculative guess that has yet to be tested.
Lacking direct evidence, a genealogical proof is something that is written. Historically speaking, the work considers the full range of evidence relevant to the problem.
My own family history follows a mostly narrated style. As with the author of fbrereto's material, there are relationships in my tree that can be documented (with a source about something), but those relationships are yet to be proven (genealogically speaking).
At least I find these pose the greatest challenge in database presentation. As part of current work on "one-tree" systems, I've been trying to advance my own approaches to database presentations about notions of hypothesis, theory and proof. An example follows about the comment I add to a conclusion that I deem a hypothesis:
Dr. Charles Banks (History of Martha's Vineyard) concluded that
Dorcas Bessey, daughter of Anthony, was the wife of John Presbury (d.
1679 of Saco). Others either dispute the notion or find material
unresolved conflict. This includes that Robert Charles Anderson, The
Great Migration Project (for Anthony Bessey), did not report any
spouse for Dorcas. Lacking a genealogical proof, I conclude that the
wife of John Presbury (d. 1679) is only possibly, not probably, Dorcas
Bessey.
I consider this a hypothesis because even if I have the materials they worked with, I do not have the experience of Banks, Anderson, etc. On the other hand, I probably do have more information about the "whole" persons/families generally associated with John Presbury (d. 1679). In other words, I may have information or context that Banks, Anderson, etc. did not have; there is probably more that could/hopefully will be discovered.
It's possible that I could further develop those various materials in such a way that it would constitute a theory. Until then, I consider conclusions about Dorcas Bessey and John Presbury (d. 1679) to be just a hypothesis.