View file PF.Base/module/feed/install/version/3.0.0.xml.php

<upgrade>
	<phpfox_update_settings>
		<setting>
			<group />
			<module_id>feed</module_id>
			<is_hidden>1</is_hidden>
			<type>boolean</type>
			<var_name>allow_comments_on_feeds</var_name>
			<phrase_var_name>setting_allow_comments_on_feeds</phrase_var_name>
			<ordering>1</ordering>
			<version_id>2.0.0alpha3</version_id>
			<value>1</value>
		</setting>
	</phpfox_update_settings>
</upgrade>