mail forwarding settings missing from alias option

hello all -

this is a reposting from: https://www.virtualmin.com/node/28098 since my question has morphed.

when i create a sub-server, i have the "mail forwarding" option available, but when i create a VS with the "alias-with-own-email" i do not.

please see attached sub-server.png and alias.png.

could anybody please tell me why alias-with-own-email does not have the "mail forwarding" options?

my temporary workaround: i can simulate the 'alias-with-own-email' VS using the sub-server option by creating a symbolic link:

mv --verbose    /home/parent.com/domains/child.com/public_html     \    
                        /home/parent.com/domains/child.com/public_htmlRENAMED     ;
ln --symbolic   --verbose       ../../public_html                                                   \                                                            
                                           /home/parent.com/domains/child.com/public_html  ;

however, i would rather have virtualmin take care of this for me.