Oh, your question just solved my idea, I noew re-structure for my blog, move niche's posts to niche's subdomain (eg: posts about Woodworking will move to https://moc.chebinhdan.com). Now its very clear for me and you:
1. Create a new blogspot (https://mocbinhdan.blogspot.com)
2. Add 3rd party subdomain to it: https://moc.chebinhdan.com (updating)
3. Clone ...