email address with domain alias

Getting to terms with DMARC I've noticed that sending reports to an external domain requires the external domain to have a DNS TXT entry permitting this. this however means I need to create a TXT entry for each sending domain in the zone file of the receiving domain. Great if you don't have many domains to cater to.
So, I think I'd prefer to have the reports sent back to the same domain but don't want to create a mailbox for this for each domain. My users after all expect me to manage this for them and I don't like the admin work of lots of email accounts to manage.
Enter the user alias (dmarcreq@), as opposed to the domain catch all alias "@example.com". I think this is what it would look like: "/^dmarcreq@/ dmarc_admin@admin_domain.com". But where to put this? The ISPConfig email alias interface doesn't allow for regex entry. I could manually insert something in the mysql table, but rather I'd add a file in /etc/postfix/ and set the custom alia- there. What would the best way be of setting this alias so any email to dmarcreq@* is forwarded to a single account?
(ISPConfig 3.1)

 

Simple non mySQL solution:
To allow each domain to receive DMARC reports on their own domains (no need to add lots of TXT reconrds to the maizymoo.com domain, we install portfix-pcre, create a PCRE file and add it to main.cf.
Install postfix-pcre:
sudo apt install postfix-pcre
Create /etc/postfix/dmarc_aliases.pcre:
vi /etc/postfix/dmarc_aliases.pcre
Paste the following into the new file:
# RUA catch-all
/^dmarc.aggregate@/ dmarcreq@<your_admin_domain.com>
Add pcre:/etc/postfix/dmarc_aliases.pcre, to the start of the virtual_alias_maps string in /etc/postfix/main.cf:
[...]
virtual_alias_maps = pcre:/etc/postfix/dmarc_aliases.pcre, hash:/var/lib/mailman/data/virtual-mailman, proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, proxy:mysql:/etc/postfix/mysql-virtual_email2email.cf
[...]
Restart postfix:
service postfix restart