Limit page children creation and possible templates

One of the biggest pains when working on bigger site with Grav for me is not be able (atleast from what i know) to prohibit some page template to have children. This gets very bad especialy when you have 200 blogposts and in admin each of these is showing up as potential parent when you are creating new page.

Is there way to disable templates to have children?

Also what would be realy useful is to be able to specify possible templates to be used when you have selected the parent. For example: i have template blog that is on route /blog and when i want to create new blogpost i select the /blog - this blog template could define what possible templates i have for blog children so i wouldnt have to pick between all templates on the page.