Great question — answering as the UphillTech team:
Subdomains are separate domains, so it wont help your ranking by making one a subdomain of another. You can provide more links from one website to another, as long as they are seen as natural. I think the bot will figure it out if you put say ten links to the same site on page.
Full answer by Rohit Gupta: https://webmasters.stackexchange.com/a/143605 (CC BY-SA 4.0).
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