After the merger of two companies, was there an extra site, a stub or a redirect?

Question

Search Engine Optimization

Hello everyone, this is the situation.
There were two companies that were engaged in the same "advertising" each company had websites. But recently these companies have become one by choosing the name and everything else, now the site of the second company is left out of the lot. Once they invested in it for promotion and so on, now clients come there.
What is the best way to do it in terms of seo, put a stub with information on the main page and a link to the main site or .htaccess to automatically redirect to the main site, can you tell me a more correct way.
I would like not to lose it in the search results.

Answer 1

If you just make a 301 redirect without explaining the reasons, there will be a lot of misunderstandings, the stub will solve this problem. It will not be able to keep traffic for a long time, if the contacts of both sites are the same, an affiliate filter may come. The ideal solution for a while while there is traffic to the site is to put a through banner or block with information in the header that there was a merger and the site moved. As the traffic ends, then make a redirect to the main domain.