Steven's answer is very good, and I'm sure it's what every adopted parent would want, and probably what most good parents would want.
But we have to mention the big downside here, and that is that it completely breaks the DNA support. The fact that the father decision has been left to the profile manager means that parts of WikiTree are true to the actual family structures, including non-biologically related, and parts of WikiTree are biologically true, fully DNA supportive. That inconsistency is really regrettable. The tree should be one or the other, and if it wants to truly and fully support all DNA features, it is going to have to require biological parentage only. That is naturally going to be strongly resisted, unless we make the following change.
There's only one good solution, and that is that at some point, WikiTree profiles MUST be able to include multiple fathers and multiple mothers, both biological and non-biological, appropriately marked. That means that any person could have multiple roles in life - a male could be a biological father of one child, then a step-father to another child, then an anonymous sperm donor to a third child, then change genders and be a step-mother to a fourth child (my sympathies to whomever has to document that!).
We all appreciate the extra work for our WikiTree devs, but I don't see any other course. It has to happen.