Get Flag from another WD Component

Hello,

I create an IFRAME UI-Element in WD Componet (A1), and within this Iframe will be displayed another SAP WD component (B1).

now i want only send a FLAG from WD Componet (B1) to WD Component (A1).

I tryed to do this by creating a singelton Class with Public Static Boolean Attribute. and the Class will be called in Both component, BUT unfortunately i dont get this Flag in the component (A1).

can you please show me if I miss something with singelton Class? or is there another way to get that Flag back in the Component (A1)?

do I need to create Comp Usage to make this work?

thank you very much