TYPO3 Core

As of version TYPO3 9.5.3 with this settings:

flexform.xml

...
<settings.selection>
    <label>Test</label>
    <TCEforms>
        <config>
            <type>select</type>
            <foreign_table>tx_myext_domain_model_record</foreign_table>
            <foreign_table_where>tx_myext_domain_model_record.pid='###PAGE_TSCONFIG_ID###'</foreign_table_where>
            <renderType>selectMultipleSideBySide</renderType>
            <wizards>
                <add>
                    <type>script</type>
                    <title>New</title>
                    <module><name>wizard_add</name></module>
                    <icon>add.gif</icon>
                    <params>
                        <table>tx_myext_domain_model_record</table>
                        <pid>###PAGE_TSCONFIG_ID###</pid>
                        <setValue>prepend</setValue>
                    </params>
                </add>
            </wizards>
        </config>
    </TCEforms>
</settings.selection>
...

page.tsconfig

TCEFORM.tt_content.pi_flexform.myext_pi1.sDEF.settings\.selection.PAGE_TSCONFIG_ID = 42

The setting for PAGE_TSCONFIG_ID is respected in the foreign_table_where-clause.

However, in the add-wizard the setting isn't respect, only

TCEFORM.tt_content.pi_flexform = 42

is taken into account.

In my opinion the code in \TYPO3\CMS\Backend\Controller\Wizard\AddController:162-171 is responsible and needs some work.