Solved:
I solved it only with Plesk - I got a german Tipp here:
http://sc.hokola.de/e-mail-einrichten-fur-subdomai ns-mit-plesk-8/
Simply create at first two subdomains - each as a main domain, then create the former main-domain as a subdomain of one of them.
Then you have two ftp-accounts and emails for all
i.e.:
sub1.domain.tld (in Plesk as a main domain created)
sub2.domain.tld (same)
domain.tld (in Plesk created as a subdomain of one of them)
But anywhy - I like Powertoys with its lot of useful tools.
Thanks
Beda