EE Using Cloud Flow Designer.

I've created a flow to collect information from clients. Part of this form will ask for the Shipping and Billing addresses...

I have both blocks on a single "Screen"

I have also added a checkbox labled "Same as Shipping" just below the the Shipping Address block (just above the Billing address block)

Currently (using a decision) if the CBX is true, I can "Assign" the Shipping Address info to the both the Shipping/Billing var... Fields, but to the user, the Billing address fields remain blank. so they think the form (cbx) didn't work, and proceed to fill in the billing address information anyway, and they are complaining about this not working... 

So my questions are:

Is their a way to have a single screen dynamically update information on the screen page, following a checked box event?

I'm inclined to assume I can do this via some apex class/testclass, but don't have the apex expertise to create something like this. And given this type of functionality is so wide spread (almost fundamental), I'm hoping their is a sample/working class in jithub, I've tried searching jithub, but either I don't understand how to or their arent nearly as many apex references as I was expecting to find. Or Maybe Apex isn't the right option, I say that because I'm using the formatphoneplugin (which works great) but again the user, does't see the formatting change, similar to what we see when editing a phone in sf) so maybe having dynamic functions isn't supported...  But I would really love to add if it is...

Can anyone help me understand how to acheive this functionality...

And can anyone share searching tips for searching jithub.

Thanks!