I know the expanded Relationships tab was just released but I didn't see another bug report that matched it.
#1-If a character has only one known PARENT, then all of their listed siblings automatically become "Half-Siblings".
-This is a problem. In many games/stories, the parent may be known but not fleshed out yet for various reasons. But there is no way to remove that "Half-Sibling". And if it's a MYSTERY PARENT (fairly common trope), World Anvil can't deal with it except by means of a Generic Article. I play Pendragon and whether someone is a half-sibling or not is important. At the same time, I don't have time or energy to name and provide DOBs for every noble lady out there. I can think of many scenarios where this creates a problem.
#2 | If only one Parent is fleshed out, then the system breaks if you try to manually add a sibling.
I tried to get a img of the error message but now its just closing out the window. The system really does not like open-ended possibilities ;-)
The error message is in bright red when you try to add a sibling or other relative to a Single Parent and it says "Both Parents Must Be Identified..." And that's a major issue.
#3 | If No Parent Is Identified For A Character A Sibling Cannot Be Added (Not Even A Half).
So no Orphan brothers.... It won't let orphans can't be siblings now. What if their parents were generic cosmic forces or elements or something else that isn't a character.
As mentioned above, it is also really clunky even adding a Sibling to someone with one Parent. Only works about 1-out-of-5 times.
Here's the error message!!!
You must set both Biological Parents and/or both Adoptive Parents to continue.-This Error Message does not allow you to click-through or clear it without fixing it.
Make a Three Test characters (1,2,3). Now try and make C1 the parent of 2 and 3, then try and manually make 2 and 3 siblings.