[Flow] Problem deleting model that extends Party

[David Sporer]

Hi,

I have a model called CustomerUser that
extends \TYPO3\Party\Domain\Model\Person
Now when I try to delete an instance of CustomerUser I always get the
following error:

Uncaught exception #23000 in line 754 of
C:\xampp\htdocs\notifier_flow3\Packages\Framework\Doctrine.DBAL\Classes\Connection.php:
SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or
update a parent row: a foreign key constraint fails
(`notifier_core_flow3`.`sporerwebservices_passbookpasses_domain_model_customeruse_ca150`,
CONSTRAINT `FK_1763C8588F0B9145` FOREIGN KEY (`customeruser`) REFERENCES
`sporerwebservices_passbookpas)

Any hints how to solve this?
I tried to delete the referenced account first. What works is if I set the
cascading on database level but afterwards my doctrine migrations/updates
don't work anymore.

Best regards
David