how to move variable from a FTL file to a Screen

[Patrick]

In my FTL file I call
${screens.render("component://common/widget/CommonScreens.xml#AddProducerToFacility")}

but I need the variable facilityId at that screen level.  In my FTL I
tried this

<#assign parameters.facilityId="4"/>
<#assign context.facilityId="4"/>

and various other combinations.  How can I pass a variable from an FTL
to a screen?