Great stuff! I've been working on an app to help solve this same problem more generally. Here is a blog post I wrote talking about the problem from my perspective https://medium.com/look-what-i-made/4e667ad7a098
For two years, my roommate and I hosted drinks at our house every Wednesday night; the effort of continually remembering to add people to an email list + calling + texting was a drag. We were always trying to find ways to reduce friction for the event, and a similar setup would have been fun.