The old site has moved to a subdomain - what actions are needed in terms of SEO?

Question

Search Engine Optimization

I posted a new site on the main domain.
And the old one moved to a subdomain.

What to do in order not to lose modest positions on the old site?

1) Set up redirects to the addresses of the old site on a subdomain?
2) Add an old site on a subdomain to Yandex.Webmaster and Google Console?

What else?

Answer 1

So you need to transfer all positions to the new one, and not to the old one, and concentrate on this