It would be awesome if you could select what authentication position you wanted to route traffic from the parent app to.
For example, we use a SAML authentication against our school's Gsuite accounts for students and staff and parents use authenticate with Canvas credentials. Because of this setup, we've put the SAML auth to the first position. However, it's my understanding that the Canvas parent app automatically routes to the authentication that is in the first position, using the main url assigned to the school. While the solution of a discovery page exists, the ability to push the parent app to the correct authentication would eliminate the need to create one and give everybody a few less clicks.