DSpace7 - how do changes in submission-forms.dtd (added tags) become effective in .xmls of submission-forms?

[Alex Vahrenholz]

Hi,
we have a test instance of DS7 running in docker containers.
If additional tags are added in the submission-forms.dtd
(like this:
<!ELEMENT row (field|relation-field|infoText)+ >
<!ELEMENT infoText (#PCDATA) >
)
and the new tag infoText is added in one of the many [submission-form_x].xmls,
a pipeline is triggered which tries to restart all containers needed for DSpace.
But the restart does not work, the validation of the .xml against the .dtd gives an error message about an unknown tag.
Seems like the changed submission-forms.dtd is not read / initialized anew.

How to fix / force this?
Is the extension of the .dtd a realistic option that is intended / provided in the DSpace environment at all?
Found nothing about this in the docu or anywhere else.
Any help much appreciated.

Best regards