[Vuejs]-Do child routes require the same params as all other routes?

params are ignored if a path is provided, which is not the case for name or query. So with using path instead of name in your :to="{}, you dont have to provide a param.

(The problems with params is because they are nested. You could take a look and consider if you really need to have Landing as a child here, if restructuring is an option for you.
There is also an option to add a ? In the end path: "engagement/:engagementNum?” if having an optional parameter is a valid solution for you.)