PS -- I finally found the real reasons I can't do this in an answer by Chris Whitten in Jan 2019: "Sorry, WikiTree isn't set up to handle this in the data fields. (It's an uncommon situation, so allowing it would allow the more common mistake of entering marriages twice or neglecting to merge them.)" I wasn't able to find the answer in my searches because I wasn't framing the question correctly. So -- thanks to all who read and answer me. I will just use the 1st marriage and divorce because it produced the children, then record the 2nd marriage in the bio sections of both. Thank you all!