Were you publishing a project wiki or a code wiki? Can you share a screenshot of your current project Overview -> Wiki to help understand the wiki page structure and how those pages are displayed?

Here is the wiki page structure I created based on your description, You may try using the URL rather than the relative path of the sub page abcd in the markdown syntax. When I click on the link from page1 it will redirect me to the abcd sub page.

- **[abcd](https://dev.azure.com/<YourADOOrgName>/ProjectA/_wiki/wikis/ProjectA.wiki/125/abcd):**