Migrating blogs after an acquisition

Hey all! My expertise in SEO is more focused on the on-page/content production side of things, so I wanted to ask a question one of my clients posed. This client (let's call it Company X) is a start-up that was recently acquired by a much bigger corporation (let's call it Company Y). Company Y wants to migrate some of Company X's high-performing blog posts to its site, but isn't sure what to do with the rest of the blog posts it decides not to migrate. My client asked if I could provide some best practices and recommendations here. Obviously, I plan on telling them that they need to consult an SEO professional who has experience in post-acquisition migrations/redirects, but if anyone has general tips I can relay, I'd greatly appreciate it!