Provider for Siblings and Parent suggests are not working for simple cms pages

[ElectricMaxxx]

Both providers are trying to create the path by the route base path, which is usually /cms/routes. Pages persisted with the CmfSimpleCmsBundle strore nodes, whoere the routes/menu/content is available under /cms/simple. So we won't get any results by them.
We could simply add own providers or fix the code to be aware of both posibilities.

[ElectricMaxxx]

You can see that behaviour when checking out my currently WIP PR for the website

[dbu]

could we use multiple base paths like the route matcher is doing?