issues have been raised a number of times about unlikely relationships and conflicts between sources. I was pretty sure there was general guidance on WT and I have now found it. It was staring me in the face. It applies to all information relating to profiles, not just relationships, and to both pre- and post-1700 profiles. It gives explicit support to what probably most of us do automatically.
Briefly, unlikely information should not be given credence, and, where there are conflicts of evidence, we are asked to go with the better evidence if that can be determined (with explanations if appropriate on the profile). It may be helpful to quote the guidance at length.
From https://www.wikitree.com/wiki/Help:Uncertain: ”Uncertain is generally not for unlikely information. [The bold typeface is in the help page - the statement is emphasised.] If one set of facts is more likely than another it should be replaced in the data fields. If facts are unlikely but there is no more-likely information, it can be removed…."
From https://www.wikitree.com/wiki/Help:Disagreements_about_Certainty, to which there is a link in the preamble to the help page https://www.wikitree.com/wiki/Help:Uncertain_Parents:
Should you replace uncertain information added by others?
If there is more evidence for one set of facts over another, the information should be replaced in the data fields.
Ideally, we want the best available information in database fields, and we want all the evidence for and against all facts that have been associated with the person fully explained in the text. Explanations that debunk common myths can be especially valuable…
This may well cause controversy if you weren't the one who added the earlier information. See Communication Before Editing for tips.
Even though it can lead to conflicts, please improve upon information when you can. Resolving conflicting information is the height of genealogy collaboration on WikiTree. It's what our community is all about. Remember that the other member has also signed the Honor Code that says, among other relevant points: II. We care about accuracy. We're always aiming to improve upon our worldwide family tree and fix mistakes.
Should you remove uncertain information added by others without replacing it?
Removing information that someone else added when you don't have demonstrably better information is especially delicate.
As explained on Uncertain, you can remove uncertain information added by others if it is unlikely to be true. However, if the other member is responsive and is trying to follow WikiTree rules and policies, just like you, do your best to reach an agreement with them. Don't just remove the information. Try to convince them that the information is highly unlikely. Show them your sources and discuss them, in a patient, friendly way. You both want the same thing: a profile that's the best it can be.
See Communication Before Editing and Resolving a Disagreement for tips. See Problems with Members if necessary.