If you're trying to build a link wheel, it's not gonna work. Not in 2020.

What exactly do you mean by subdirectory based multisite?

Both pages,

domain.com/a
domain.com/b

are considered related, part of the same website.

Subdomains are treated as separate websites (99%, they still do share root domain obviously).

Hi @ms, thanks for your reply. With subdirectory based multisite I mean a multisite network where subsites are hosted in folders of the main site, like: mainsite.com/site1; mainsite.com/site2... Now, the point is that apparently Google tends to read those multisites as one single site but it also might distinguish different sites on the network if the content suggest they are different (as stated by John Mueller << if you have different sites that are essentially completely separate websites but they’re in subdirectories … then we’ll try to figure that out as well. And say, well, actually these are … separate sites that should be treated completely separately – then we’ll try to figure that out as well. So that’s not something that would … like improve or hurt rankings. It’s more a matter of us figuring that out. And so far I’ve seen our algorithms do a pretty good job of that.” >> https://youtu.be/onNwqFa-e_s?t=2947 )... I understand that means that Google could read linking between sites in subdirectories as internal linking in case it sees the network as a single site, but the same structure of links could be read as a link wheel if it makes out they are different sites... I am not interested on hiding they all make part of a network, in fact I'd prefer Google thinks they are all part of the same single website. The only reason I installed them on subdirectories is because that gives me more flexibility to use different themes, plugins, and I have always the option to "convert" them into separated sites with just mapping a domain to them. So is it there a way to tell Google: "This subsites make part of the same macro-website, links between them should be read as structural internal linking of the network"?

Any answer to this?

Hi. I have been surfing the web thoroughly searching a clear answer on wether interlinking sites within a multisite is it good or bad for SEO. I found info about this subject is scarce and confuse. Some SEO experts consider that interlinking between subsites could be read as a black-hat practice by Google, but on the other hand, the very structure of a multisite based on subdirectories somehow encourages -and often needs- links to the different subsites from the main site, and it might be useful to refer to contents hosted on other sites to avoid repeating content across the network. As John Mueller said, google rejects overlapping content between sites on a subdirectories mulsite, and at the same time, it tends to consider this sort of networks as one single macro-site. I think that a recap of the current state of the art could be extremely helpful.