How to deal with identical sites of the same company when promoting?

Question

Search Engine Optimization

The situation is the following. The company has 4 sites: an online store , from which the main traffic comes and 3 sites that have not been touched for 5-6 years since the first promotion: an affiliate site and 2 distributor sites . The traffic of the last three sites safely tends to 0. Does it make sense to raise these sites and link them to each other?
PS: In addition to the fact that the company is engaged in the sale of components in the industrial field, it also provides services in this area. As for me, it makes sense to leave the main site as an online store, and make the affiliate site like a landing page with the services offered, and subsequently link them to each other, and simply close the last two.
Please tell me what is the best way to proceed in this situation?

Answer 1

If there are no budgets and a desire to take the first 4 lines of search results for branded or specific queries in a niche, then the best solution would be to remove all domains except the main one (301 from all to the main one). To create landing pages for services, a much better solution would be to use subdomains rather than separate domain names.

Answer 2

There is a SEO plan and money for four, promote four, no, leave one and move only it