Can I run Families on multiple devices for no extra cost?

[malgre]

I purchased and installed Families on my iPhone. I now have an iPad and would like to load it there as well. Can that be done without purchasing another copy?

Yes, you can install it for no extra cost providing you connect to the App Store using the same login you used for the original purchase. If you select the Purchased tab, the app should be listed and you can install from there.