There are a few ways you can make a secondary blog your primary blog on Tumblr. The first is to create separate blogs for each topic you’re interested in, and then use Tumblr as an outlet to share your thoughts and ideas on each one.
This approach allows you to have a lot of control over the content you publish, and it also allows you to focus on specific topics without feeling overwhelmed by the amount of content you have to produce.
Another way to make a secondary blog your primary blog on Tumblr is to use Tumblr as a tool for promoting your main blog. When you create a custom Tumblr account and set up your blogs in the same account, Tumblr will automatically promote your main blog posts across all of your different blogs.
This can help to increase traffic and visibility for your main blog, which can help to boost its SEO ranking and increase its reach.