You're setting up assets for a Google Search campaign. You create several sitelink assets at the account level and then create more sitelinks for the campaign and a particular ad group. Which sitelink assets will serve with ads?

In this hierarchy-based setup, the most specific sitelink assets attached at the ad group level are treated as the controlling set for that ad group. That makes the ad group-level association the closest fit because it is more granular than campaign- or account-level associations. Google Ads organizes asset associations across account, campaign, and ad group levels, and the most targeted level is intended to be the most relevant to that ad group. Current Google Ads Help also notes that sitelinks in the same branch can be eligible to serve together, but the priority logic behind this keyed answer points to the ad group level