I have a collection of CDs that I ripped to mp3 to listen on my android phone. My kids want to listen to some of them on their android phones as well. Is there a way to share my mp3 collection with them so they can also play them on their own android devices? Is there a way to create a family library of mp3s for sharing across all the family's android devices?
The first thing that comes to mind is network-based sharing. A common solution is Plex.
Ideally you would install Plex Server on a device that is on 24/7, like a NAS/router/home server. Then install Plex Clients on each device and connect with the Server. The added advantage is Plex allows connections from over the Internet if you configure it to do so. So you can access the songs from work/school/car etc.
If you don't want to set up the full-time Plex Server, but just share from your phone over LAN, then you can also use the Plex client on your phone to serve the files. But using the client to serve means it is UPnP, so not easily accessible over the Internet. (You can't install Plex Server on Android OS).
TLDR; install Plex clients on all your devices. This solution is not free. If you just want LAN sharing, there are free DLNA apps like bubbleupnp. I personally use a Servers Ultimate server with Ginkgo DLNA clients. Ginkgo is very small if your family just want to consume your content.