Welcome to the forum. I am praying also.
I too would suggest that the solution may not be a church for polygamous families (which will look like a cult and put you in danger of even more persecution once discovered), but rather a home-church movement that is focussed first on Yeshua, but does not reject polygamous families, without even needing to have a firm stance on polygamy as a matter of official doctrine just a willingness to accept that views can differ on this so polygamists are accepted.
I would be very interested in any more information about yourselves, and how we may be able to support you. Central Asia is an absolutely massive place, and a critical mission field where the church is expanding rapidly, as small home fellowships, under varying degrees of oppression depending on the country and the dominance of Islam locally. It's also so big that there should be plenty of opportunities for Christians to find a place of refuge and survive through whatever may come in the future.