I don't know if this is a good idea or not, but I'll say it anyway and you can work that out for yourselves!
https://www.polygamy.com/ is a polygamous dating website built by a Muslim from the UK, but aimed at people of any religion. Given that it started out in the UK, it may have attracted others who are in your part of the world. You could sign up to that briefly simply to scout out whether there are any other Christian families seeking other wives in your area, and then make contact with them. It's a long shot but it might be worth a look.
https://www.polygamy.com/ is a polygamous dating website built by a Muslim from the UK, but aimed at people of any religion. Given that it started out in the UK, it may have attracted others who are in your part of the world. You could sign up to that briefly simply to scout out whether there are any other Christian families seeking other wives in your area, and then make contact with them. It's a long shot but it might be worth a look.