anchor in URL

In the top of main container of a webpage I have the code

<a name="begin"></a></p>

Within the page I can jump to the top of the main container by means of the the code href="begin" at the end of the page in the backend. This changes into http://localhost/contao-2.9.4/ledenlijst_2.html#begin in the webpage at the frontend.

Now I want to put ledenlijst_2.html#begin in the page alias. In order to jump to this page position after the page has been selected by means of the menu.
However Contao does not accept # in the page alias.
I also tried the externel and internal re-direct. But I was not bale to solve this problem.

Does anybody know I to realize this functionality in Contao.
Thanks.