Copyright legislation varies between jurisdictions, ie Australian copyright is different from US copyright, diiss different from British Copyright. (I was involved in managing copyright for a multinational company so have a clear understanding of what this is about).
Firstly, if the article is out of copyright or within Creative Commons it can be used, but always acknowledge Sources.
Secondly, if it is within copyright then in most cases up to 10% of the works may be copied “for personal use”. WikiTree is not for personal use, but it is also not for commercial use either. Rather than going into detail about non commercial usage, I understand that short quotes, with source is acceptable, as you would see in a published book.
My recommendation is that you add inline references to the sources so that it doesn’t become full of referencing in the text.
When I add long quotes from BMD Sources I add it to the reference not to the text.
See [[Crane-2899|William Crane]